The 1975 Elastomer Bumper Developed by BASF and used on the MGB

 

On the 1975–1980 MGB “rubber bumper” cars, the big black bumpers were made from a BASF polyurethane system—specifically a reaction‑injection‑molded (RIM) polyurethane elastomer (often described in period sources as “BASF polyurethane” or “BASF Elastomer” bumpers). They were mounted on steel structures/energy absorbers, but the visible bumper skin itself was polyurethane.

Most enthusiasts—especially in the U.S. and among “classic chrome-bumper” traditionalists—viewed the 1975 MGB’s rubber bumpers as a necessary regulatory compromise that hurt the car’s looks and character, even if they understood why MG did it.

The dominant enthusiast reaction: “uglier and less sporty”

• Aesthetics: The thick black polyurethane bumpers were widely seen as visually heavy compared with the slim chrome blades. Many felt they made the MGB look taller and more “blocky,” diluting the 1960s roadster elegance.
• Proportions/ride height: To meet U.S. 5‑mph impact rules and bumper-height requirements, MG raised the car’s ride height. Enthusiasts often complained this made the car look “jacked up” and reduced the planted, sporty stance.

Driving/handling perceptions

• Higher center of gravity + softer setup: The raised ride height and suspension changes were commonly blamed for a small but noticeable loss of crispness in turn-in and overall feel compared with earlier cars.
• Weight and balance: The bumper system added weight at the ends, and enthusiasts often described the later cars as feeling a bit less lively (even if the difference in normal driving could be subtle).

The “it’s not just the bumpers” argument

Many owners also point out that the mid-1970s MGB changes came as a package:

• emissions-era tuning that reduced power (especially in U.S. spec),
• additional safety/comfort equipment,
• and the bumper/ride-height changes. So in enthusiast memory, “rubber bumper” became shorthand for the whole late-’70s compromise era, not only the bumper material itself.

A more nuanced, current, minority view

• Practicality: Some enthusiasts appreciate the rubber bumpers for real-world use—parking protection, less worry about minor knocks, and cheaper replacement compared with chrome.
• Value entry point: Rubber-bumper cars have often been cheaper, making them a common gateway into MGB ownership.
• Easy to improve: Many owners lower the ride height and upgrade suspension, which can recover much of the handling feel while keeping the later car’s usability.

Overall, the enthusiast consensus has long been: chrome-bumper MGBs are the “pure” look, while the 1975-on rubber-bumper cars are the regulations-and-emissions compromise—sometimes loved, often modified, and still very much part of the MGB story.

Materials involved (what BASF supplied / what the bumper was made from)

1) Polyurethane elastomer (RIM) This is the main “rubber” you see.

• Chemistry (typical for 1970s RIM PU):
  • Isocyanate component: commonly MDI-based (methylene diphenyl diisocyanate) prepolymers in many automotive RIM systems of the era.
  • Polyol component: polyether polyols were common for elastomeric RIM, combined with chain extenders to tune hardness.
  • Catalysts: amine and/or organotin catalysts (used in PU processing generally).
  • Additives: carbon black (for color and UV), stabilizers/antioxidants, internal mold release agents.
• Why PU RIM: it could be molded into large shapes, had good impact resilience, and could meet 5‑mph bumper requirements without a heavy chrome-plated steel assembly.

2) Pigment/filler package Most MGB bumpers were black-through or black-finished.

• Carbon black was the key pigment and also helped UV resistance.
• Fillers could be used to tune stiffness/cost, depending on the exact BASF formulation.

3) Substructure (not BASF, but part of the bumper system) Behind the PU skin, the MGB used:

• Steel reinforcement/beam and mounting brackets
• Energy absorbers (often hydraulic or crush elements depending on year/market) These are crucial to how the bumper worked, but BASF’s role was the polyurethane elastomer system.

The History and Development of Mercedes-Benz Interior Synthetic Upholstery MB-Tex

 

MB‑Tex is Mercedes‑Benz’s long-running synthetic upholstery—often mistaken for “vinyl” in the generic sense, but in practice a high‑durability coated fabric engineered to look like leather while outperforming it in wear and maintenance. Its post‑WWII development is best understood as a response to three pressures Mercedes faced in the 1950s–60s: rebuilding production under material constraints, expanding exports (especially to the U.S.), and meeting customer expectations for interiors that could survive heat, sun, and heavy use with minimal care.

Postwar context: why a premium brand would push a synthetic

In the late 1940s and early 1950s, Mercedes‑Benz was rebuilding its product line and supply chains. Leather was expensive, variable in quality, and labor-intensive to cut and stitch. At the same time, the company was moving into higher volumes and broader markets. A synthetic seat material offered Mercedes something strategically valuable: standardized quality. If you can specify a roll good with consistent thickness, grain, and color, you can scale production and reduce warranty issues—especially for taxis, fleet buyers, and export customers.

What MB‑Tex is (in construction terms)

While Mercedes has not always published a single, simple recipe (and suppliers and formulations evolved), MB‑Tex is generally described as a vinyl-based (PVC) surface bonded to a textile backing. The “Tex” in the name reflects that it’s not just a sheet of plastic; it’s a composite upholstery material:

• a coated top layer that provides the leather-like grain, color, and cleanability
• a fabric substrate that provides dimensional stability, tear resistance, and sewability

This coated-fabric approach is a key reason MB‑Tex gained its reputation: it behaves more like a durable upholstery system than like cheap, thin vinyl.

Development in the 1950s–60s: from substitute to brand standard

Mercedes introduced MB‑Tex as an option/alternative to leather in the postwar era and it became widely available by the late 1950s and 1960s across sedans and coupes. The development emphasis wasn’t “luxury feel” first; it was durability under real service:

• resistance to abrasion (sliding in/out, clothing wear)
• resistance to UV and heat (critical for sunny climates and U.S. markets)
• resistance to staining and moisture
• colorfastness and consistent grain embossing

Those targets align with Mercedes’s broader brand promise at the time: cars engineered for longevity and heavy-duty use (including the famous European taxi market). MB‑Tex fit that identity perfectly: it was a premium synthetic because it was engineered to last, not because it was trying to be “soft.”

Why it succeeded: performance and economics lined up

MB‑Tex became notable because it solved problems that leather didn’t:

• Heat/sun tolerance: Leather can dry, crack, and fade if neglected; MB‑Tex was more forgiving.
• Maintenance: It could be wiped clean easily, a major selling point for families and fleet users.
• Consistency: Fewer natural defects than hides; easier to match panels and colors.
• Cost positioning: It allowed Mercedes to offer a “Mercedes interior” at a lower price point than full leather while still meeting durability expectations.

In other words, MB‑Tex wasn’t merely a cost-cutting substitute; it was a way to deliver Mercedes’s durability narrative in material form.

Design and perception: the “Mercedes way” of synthetic luxury

A critical point is that MB‑Tex also reflects a cultural difference in luxury. American luxury in the 1950s–60s often emphasized plushness and novelty; Mercedes emphasized engineering integrity. MB‑Tex could feel firmer and less “rich” than leather to some buyers, yet it aligned with Mercedes’s functional, long-life ethos. Over time, that created an unusual status: MB‑Tex became a kind of insider badge—owners would brag that it “wears like iron,” especially on high-mileage cars.

Evolution after introduction 

As regulations and customer expectations changed, Mercedes and its suppliers improved:

• plasticizer and stabilizer packages for better aging/less cracking
• embossing and grain patterns to look more leather-like
• backing fabrics and foam interfaces for better comfort and fit
• broader color palettes as interiors became more style-driven in the late 1960s

• Mercedes didn’t publish an “MB‑Tex additive list,” and formulations varied by supplier and year, so we can’t name a definitive MB‑Tex recipe. But MB‑Tex in the 1970s was essentially a PVC (vinyl) coating on a textile backing, and PVC automotive upholstery of that era used a fairly standard toolbox of additives. Here’s what was typical in the 1970s and why it was used:

  Plasticizers (to keep PVC flexible)

  • Phthalates were dominant:
    • DOP/DEHP (di‑2‑ethylhexyl phthalate) and DINP (diisononyl phthalate) were widely used general‑purpose plasticizers.
    • DIDP and related high‑molecular‑weight phthalates also appeared as the decade progressed. Why: flexibility, low-temperature performance, processability, “hand” feel.

  Heat stabilizers (PVC needs them to survive processing and service)

  • Lead-based stabilizers (common in Europe then): e.g., tribasic lead sulfate, dibasic lead phosphite, and related lead soaps.
  • Organotin stabilizers (especially for good color retention/clarity): e.g., dibutyltin and dioctyltin carboxylates/mercaptides.
  • Barium–cadmium (Ba/Cd) stabilizer systems (also common historically in flexible PVC). Why: prevent dehydrochlorination during extrusion/calendering and slow heat aging (brittleness, discoloration).

  UV/light stabilizers (sunlight resistance)

  • UV absorbers (often benzophenone or benzotriazole types in that era).
  • Hindered amine light stabilizers (HALS) began to appear in the 1970s (more common later, but the technology emerged during that period). Why: reduce fading, surface cracking, and embrittlement from sunlight.

  Fillers and extenders

  • Calcium carbonate (CaCO₃) was very common.
  • Sometimes clays/talc depending on target stiffness and cost. Why: cost control, stiffness/hand tuning, dimensional stability.

  Pigments and colorants

  • Titanium dioxide (TiO₂) for whites and opacity.
  • Carbon black for black and as a UV-protective pigment.
  • Other inorganic/organic pigments for browns, blues, greens, etc. Why: color, hiding power, UV durability (carbon black especially).

  Lubricants / processing aids

  • Stearates (calcium stearate, zinc stearate), waxes, and related processing lubricants. Why: improve flow, release, surface finish, reduce sticking in calendering/embossing.

  Flame retardants (sometimes)

  Automotive interiors sometimes used flame-retardant packages depending on market requirements and OEM specs; in 1970s flexible PVC this could include phosphate esters or chlorinated additives. Why: meet flammability standards and OEM internal specs.

  Bottom line

  For 1970s MB‑Tex specifically, the most likely additive “families” were: phthalate plasticizers + heavy-metal heat stabilizers (lead and/or Ba/Cd, sometimes organotin) + UV absorber package + CaCO₃ filler + TiO₂/carbon black pigments + stearate/wax processing aids.

Even without a single public “version history,” the trajectory is clear: MB‑Tex moved from a pragmatic postwar material strategy to a defining Mercedes interior option

The Use of Plastics in the American Automotive Industry after World War II

 

After WWII, U.S. automakers rapidly expanded the use of synthetic plastics to cut cost/weight, enable new styling, and improve corrosion resistance. Below are the major plastics, what they were used for, and the key U.S. companies that supplied them or commercialized them in cars (roughly late‑1940s through the 1960s).

Big families of plastics and where they showed up

Phenolics (phenol‑formaldehyde, “Bakelite”-type thermosets)

Typical parts: distributor caps/rotors, electrical switchgear, knobs, small under‑hood insulators, some interior hardware.
Why used: heat resistance, electrical insulation, dimensional stability.
Major suppliers: Bakelite Corporation (later part of Union Carbide), General Electric (phenolic molding compounds), and major compounders/molders supplying Detroit.

Urea‑formaldehyde and melamine‑formaldehyde (thermosets)

Typical parts: interior knobs, handles, some trim pieces, steering-column/under‑dash small parts (especially where a hard, glossy surface was desired).
Why used: good surface finish, colorability, stiffness (but more brittle than later plastics).
Major suppliers: resin producers such as American Cyanamid and others that sold molding compounds into automotive supply chains.

PVC (polyvinyl chloride) — rigid and plasticized

Typical parts: vinyl upholstery, door panels, dash pads/skins, wire insulation, undercoating/sealers, some exterior trim strips.
Why used: cheap, flexible (when plasticized), easy to form, good for skins/coatings.
Major suppliers: B.F. Goodrich (a pioneer in PVC), Union Carbide, and Dow (vinyl-related chemicals), with upholstery/trim made by Tier suppliers.

Polystyrene (GPPS/HIPS)

Typical parts: interior trim, knobs, bezels, some instrument-panel components (often later replaced by tougher plastics).
Why used: low cost, easy injection molding; HIPS improved impact resistance.
Major suppliers: Dow Chemical (major polystyrene producer), Koppers (styrenics), and others.

ABS (acrylonitrile‑butadiene‑styrene)

Typical parts: interior trim, instrument-panel parts, grilles and bezels, some wheel covers and decorative components (varied by maker).
Why used: tougher than polystyrene, good surface finish, plateable grades enabled “chrome-like” trim.
Major suppliers: Borg-Warner (notably via Cycolac ABS), plus resin/compound suppliers feeding Detroit.

Acrylic (PMMA, e.g., Plexiglas/Lucite)

Typical parts: lenses, light covers, some interior transparent pieces; occasionally specialty glazing applications.
Why used: optical clarity, weathering resistance, styling freedom.
Major suppliers/brands: Rohm & Haas (Plexiglas), DuPont (Lucite).

Polyethylene (PE) and polypropylene (PP)

Typical parts: wire/cable insulation (PE), fluid bottles and small containers, later more interior parts (PP grew strongly in the 1960s).
Why used: chemical resistance, low cost, toughness; PP especially for lightweight interior components.
Major suppliers: Union Carbide, Dow, Hercules (early PP in the U.S.), and others.

Polyurethane (PU) foams (flexible and semi-rigid)

Typical parts: seat cushions, armrests, headliners, energy-absorbing interior pads; later bumper cores and more.
Why used: comfort, energy absorption, moldability into complex shapes.
Major suppliers: chemical systems from Mobay (Monsanto/Bayer JV), Dow, DuPont, and foam/seat suppliers.

Fiberglass-reinforced plastics (FRP) — polyester resin + glass fiber (thermoset composite)

Typical parts: body panels on specialty cars, front ends, hoods, decklids; also truck components and some structural-ish panels.
Why used: corrosion resistance, complex shapes without expensive steel dies at low volume.
Iconic U.S. use: Chevrolet Corvette (1953) popularized mass-market awareness of fiberglass bodies.
Major resin/fiber players: Owens-Corning (glass fiber), PPG (glass), DuPont and Reichhold (polyester resins/chemicals), plus many molders.

Engineering thermoplastics emerging by the 1960s

• Nylon (polyamide): under‑hood parts, bushings, gears, fasteners; valued for wear resistance and heat tolerance. DuPont (Nylon) was central.
• Acetal (POM, e.g., Delrin/Celcon): small gears, latches, fuel-system and window hardware. DuPont (Delrin) and Celanese (Celcon). These materials expanded as under‑hood temperatures and part complexity increased.

Automakers and “where it showed”

• GM: early high-visibility composite use via the Corvette’s fiberglass body; broad interior plastics adoption across Chevrolet/Pontiac/Olds/Buick/Cadillac as dashboards and trim became more molded and styled.
• Ford and Chrysler: heavy adoption of vinyl (PVC) interiors, molded trim, and later foams and ABS/engineering plastics as the 1950s–60s styling race intensified.
• AMC/Studebaker/others: often used plastics strategically to reduce tooling cost and differentiate interiors, especially in lower-volume models.

The Development of Bosch's K-Jet Fuel Injection Technology

 It is a technology that I struggle with as I keep my 1982 Mercedes 380 SL running well. Right now, knock on wood, it is behaving in an acceptable fashion, but with high idle when hot and in either park or neutral.

Bosch’s K‑Jetronic (the “K” is from German Kontinuierlich, meaning continuous) didn’t appear as a single invention so much as the convergence of several long-running development threads: Bosch’s deep experience with precision fuel metering (especially diesel), the postwar spread of mechanical gasoline injection in Europe, and—most decisively—1960s emissions and drivability demands that were becoming hard to meet with carburetors at scale. K‑Jet was Bosch’s answer to a very specific brief: deliver near–fuel-injection precision without electronics, in a package that could be mass-produced, serviced, and certified for increasingly strict regulations.

1) Bosch’s starting advantage: precision metering culture

Long before K‑Jet, Bosch had built its reputation on components that require tight tolerances and repeatable calibration—magnetos, ignition systems, starters, generators—and, crucially, diesel injection equipment (high-pressure pumps and injectors). That matters because gasoline injection is fundamentally a metering problem: stable pressures, consistent flow, and predictable atomization. Bosch already had:

• manufacturing capability for precision pumps and valves,
• test/bench infrastructure for calibration,
• and a supplier relationship model with automakers (Bosch as systems partner, not just parts vendor).

So when gasoline injection became commercially urgent, Bosch was positioned to industrialize it.

2) The pre-K landscape: mechanical gasoline injection existed, but it was niche

By the 1950s and early 1960s, mechanical gasoline injection was already proven in Europe—most famously on performance cars (e.g., Mercedes and others). These systems delivered excellent throttle response and power, but they were often:

• expensive,
• sensitive to adjustment and wear,
• and not optimized for the mass-market problems that would soon dominate: cold starts, idle stability, and emissions consistency across conditions.

At the same time, carburetors were improving (multi-barrels, better chokes, better calibration), which meant injection had to offer not just “more power,” but measurably better control.

3) The forcing function: emissions regulations and real-world drive cycles

The late 1960s brought a new kind of requirement. Regulations (first notably in California, then federally in the U.S., and increasingly in Europe) demanded lower HC and CO emissions under standardized tests that included:

• cold start,
• warm-up,
• idle,
• and transient operation.

Those are precisely the regimes where carburetors struggle, because mixture formation is affected by:

• fuel condensation on cold manifolds,
• rapid throttle changes,
• altitude/temperature variation,
• and the need for enrichment devices (chokes, accelerator pumps) that tend to overshoot.

Automakers could and did add carburetor “patches” (more vacuum circuits, thermal valves, dashpots, air pumps, EGR later), but complexity rose quickly and calibration became fragile. The industry needed a system that could hold mixture closer to target across conditions without becoming a tuning nightmare.

4) Bosch’s strategic design choice: continuous injection + airflow-based metering

Bosch’s key conceptual move with K‑Jetronic was to avoid the hardest part of pre-electronic injection: timing fuel pulses precisely to engine events. Instead, K‑Jet uses:

• continuous fuel flow to each injector (no pulsing),
• and meters how much fuel flows based on measured intake air flow.

This is a pragmatic engineering trade:

• You give up per-cylinder, per-cycle timing precision.
• You gain a simpler, highly repeatable metering system that behaves smoothly during transients and is easier to manufacture and service than many earlier mechanical systems.

The heart of K‑Jet is the airflow sensor plate (a movable plate in the intake stream) mechanically linked to a fuel distributor. More air pushes the plate further, which moves a control plunger and uncovers metering slits, increasing fuel flow proportionally. In other words: airflow directly “commands” fuel flow through a purely mechanical-hydraulic analog computer.

5) Why Bosch went hydraulic: stability, linearity, and manufacturability

K‑Jet is often described as “mechanical,” but its real genius is hydraulic control:

• A high-pressure electric fuel pump supplies fuel to the distributor.
• The distributor apportions fuel to each cylinder through calibrated passages.
• System pressures and differential pressures are regulated so that the relationship between plate movement and fuel flow is stable and predictable.

Hydraulics let Bosch achieve:

• fine resolution (small movements produce measurable flow changes),
• good repeatability over temperature,
• and a system that can be bench-calibrated and quality-controlled in volume.

This is where Bosch’s diesel-injection heritage and precision manufacturing culture mattered: K‑Jet’s fuel distributor is a tight-tolerance device.

6) The drivability problem: cold start and warm-up enrichment

A mass-market injection system lives or dies on starting and warm-up. K‑Jet incorporated dedicated subsystems to handle what carburetors handled (crudely) with chokes:

• Cold-start injector (extra fuel during cranking),
• Warm-up regulator / control pressure regulator that adjusts “control pressure” acting on the metering mechanism.

Lower control pressure during warm-up allows the airflow plate/plunger to deliver a richer mixture; as the engine warms, control pressure rises and the mixture leans out. This gave K‑Jet a way to deliver:

• reliable cold starts,
• smoother warm-up,
• and more consistent emissions than many carbureted setups of the era.

7) The market timing: “good enough now, extensible later”

Another development that led to K‑Jet was Bosch’s need for a system that could be deployed broadly before electronics were ready (or cheap enough) for everyone. Early electronic injection existed, but sensors, ECUs, and reliability/cost targets weren’t yet aligned for widespread adoption across many models.

K‑Jet hit a sweet spot:

• It was a step-change improvement over carburetors for mixture control.
• It could be produced and serviced with 1970s technology.
• It created a platform Bosch could evolve.

That last point proved crucial: Bosch later added closed-loop oxygen-sensor control to the basic continuous-injection architecture (KE‑Jetronic), and in parallel developed fully electronic pulsed systems (L‑Jetronic and successors). K‑Jet can be seen as a bridge technology: mechanical-hydraulic core with a pathway to electronic correction.

8) Competitive and OEM pressures: a supplier system, not a one-off

Finally, Bosch developed K‑Jet in a context where automakers wanted:

• a supplier-supported, standardized system,
• with documentation, training, and parts availability,
• and predictable certification behavior.

Earlier mechanical injection often felt bespoke. K‑Jet was engineered to be a repeatable “system product” Bosch could sell across brands and displacements with calibration changes rather than fundamental redesign—exactly what a major Tier-1 supplier needs.

Putting it together

Bosch developed K‑Jetronic because the industry arrived at a point where carburetors were becoming an emissions-and-drivability liability, while full electronic injection was not yet universally practical. Bosch’s response leveraged its strengths—precision manufacturing and hydraulic metering—to create a continuous-injection system that:

• measures air directly,
• meters fuel proportionally through a fuel distributor,
• and handles cold/warm behavior with pressure-based regulation.

The most beautiful American cars of the 1970s

 

Ten most beautiful American cars of the 1970s

1.     1971–1973 Buick Riviera (“boattail”) he boldest, most sculptural American production shape of the decade—dramatic without looking cheap.

   

   
   

2. 1970–1973 Pontiac Firebird / Trans Am (2nd gen, early)

   
   
   
   Low, wide, and cleanly aggressive; great proportions before later add-ons got busier.

3. 1970–1971 Plymouth Barracuda / ’Cuda

   
   
   
   A near-perfect muscle-car stance: tight greenhouse, strong fenders, and just enough ornament.

4. 1970 Chevrolet Chevelle SS (and Malibu coupe)

   
   
   
   Simple, balanced, and muscular—one of GM’s best “no wasted lines” shapes.

5. 1971–1974 Dodge Charger (3rd gen)

   
   
   
   Sleek and fastback-like, with a distinctive, almost European smoothness for a big American coupe.

6. 1977–1979 Lincoln Continental Mark V

   
   
   
   Peak personal-luxury theater: formal lines, long hood, and a presence that’s unmistakably 1970s America.

7. 1971–1976 Cadillac Eldorado (FWD)

   
   
   
   Big, elegant, and surprisingly clean for its size; the long hood and crisp sides read expensive.

8. 1970–1972 Oldsmobile Cutlass Supreme (and 4-4-2)

   
   
   
   Crisp, tasteful, and very “right-sized” visually—arguably the best-looking of the GM A-bodies.

9. 1970–1972 Chevrolet Monte Carlo

   
   
   
   A long-hood personal coupe that looks upscale and composed, especially in restrained colors.

10. 1971–1973 Ford Mustang (Mach 1/fastback)

    
    
    
    Not everyone’s favorite Mustang era, but the long hood and fastback profile are genuinely striking.

The Most Beautiful Cars of the 1970s

 

Ten most beautiful cars of the 1970s 

1. Lamborghini Miura SV (1971–73)
   The purest supercar shape ever put on the road: low, sensual, perfectly proportioned.

2. Ferrari 365 GTB/4 Daytona (early 1970s) 

   
   
   

3. Long-hood elegance with just enough sharpness—muscular without looking heavy.

4. Maserati Bora (1971–78) 
   A clean, architectural mid-engine wedge that still feels luxurious rather than gimmicky.

   
   
   

5. Citroën SM (1970–75)
   Futuristic and graceful at once—glass, taper, and stance that look like nothing else.

   
   
   

6. Jaguar XJ12 / Series II XJ (1970s)
   A masterclass in sedan proportion: low roof, long hood, understated curves.

   
   
   

7. BMW 3.0 CS / CSi / CSL (E9) (early 1970s)
   Light, airy greenhouse and perfect coupe balance—sporty without aggression.

   
   
   

8. Alfa Romeo Montreal (1970–77)
   Quirky details (louvered headlamp brows) that somehow make the whole car more exotic.

   
   
   

9. Lancia Stratos HF (1973–75 road car)
   Short, dramatic, and purpose-built—beauty through pure intent.

   
   
   

10. Porsche 911 Carrera RS 2.7 (1973)

    
    
    
    Not flashy, just “right”: compact, taut, and timeless with the ducktail.

11. Lotus Esprit S1 (1976–78)
    The wedge distilled—crisp lines and a stance that screams 1970s in the best way.