Opel 4 Specifications: Why This Old Car Still Matters
Opel 4 Specifications Overview
The Opel 4, primarily referring to the iconic Opel P4 produced from 1935 to 1937, featured a 1,073 cc inline-four engine delivering 23 PS (17 kW) at around 3,500 rpm, enabling a top speed of 85 km/h, with dimensions of approximately 3,500 mm in length, a wheelbase of 2,315 mm, and a curb weight starting at 660 kg for the base sedan model. This compact economy car seated four passengers without a separate trunk, prioritizing affordability and fuel efficiency at 6-7 liters per 100 km. Its side-valve engine and 4-speed manual transmission made it a sales hit, with 65,864 units produced before replacement by the Opel Kadett in 1937.
Historical Context
The Opel P4 emerged in January 1935 as a direct evolution of the Opel 1.2 Liter, adapting its chassis and running gear for mass-market appeal during Germany's economic recovery. Priced at 1,900 Reichsmarks for the base model, it undercut competitors while offering standard features like a speedometer, fuel gauge, oil pressure gauge, and interior mirror-luxuries in a budget car. Opel production hit a milestone that year, exceeding 100,000 units globally for the first time, thanks largely to the P4's success among clerks and tradesmen.
"The P4 was designed on a shoestring budget yet punched above its weight in equipment and reliability, proving that economy need not mean austerity," noted automotive historian G.N. Georgano in his 1974 reference work The Complete Encyclopedia of Motorcars.
Detailed Engine Specs
- Displacement: 1,073 cc (increased from 989 cc via larger bore).
- Configuration: Inline-four, side-valve (SV), water-cooled.
- Power output: 23 PS (17 kW) at 3,500 rpm.
- Torque: Approximately 65 Nm at 2,000 rpm, sufficient for 12-14 seconds 0-60 km/h acceleration.
- Fuel system: Single Solex carburetor, 6V electrical system with 40 Ah battery.
- Compression ratio: 5.2:1, optimized for low-octane fuel of the era.
These specs positioned the P4 engine as frugal, consuming just 7.5 L/100 km in mixed driving per period tests by ADAC (Allgemeiner Deutscher Automobil-Club). Real-world data from surviving examples shows durability exceeding 100,000 km with basic maintenance.
Chassis and Dimensions
| Parameter | Specification | Notes |
|---|---|---|
| Wheelbase | 2,315 mm (91.1 in) | Identical to predecessor for cost savings. |
| Length | 3,500 mm (137.8 in) | Compact for urban parking. |
| Width | 1,480 mm (58.3 in) | Meets 1930s narrow-street standards. |
| Height | 1,550 mm (61 in) | Sedan variant; cabrio higher. |
| Curb Weight | 660-780 kg | Varies by body style; 525 kg power-to-weight. |
| Ground Clearance | 180 mm | Adequate for unpaved roads. |
| Tires | 5.25-16 | Steel rims, optional wire wheels. |
The ladder-frame chassis with live axle suspension front and rear delivered a 52/48% weight distribution, praised for stable handling at speeds up to 85 km/h on period highways like the new Autobahn network opening in 1935.
Performance Metrics
- Top speed: 85 km/h (53 mph), verified in 1935 Auto Union tests.
- Fuel economy: 6.5 L/100 km highway, 8.5 L/100 km city (equivalent to 36/28 mpg US).
- Braking: 30-0 km/h in 18 meters via mechanical drums.
- Climbing ability: 25% gradients fully loaded, per Opel factory claims.
- Range: 350 km from 30-liter tank, ideal for inter-city travel.
Independent tests by Der Motorwagen magazine in June 1936 clocked a P4 sedan at 82 km/h average over 100 km, with vibration-free cruising at 70 km/h-remarkable for a 23 PS economy car.
Transmission and Drivetrain
The 4-speed manual gearbox, a rarity in 1935 budget cars, used synchronized 2nd-4th gears for smoother shifts than rivals' 3-speeds. Rear-wheel drive via open propeller shaft and hypoid differential (ratio 4.7:1) ensured peppy low-end response. Clutch mechanism was a single dry plate, lasting 40,000 km under normal use according to Opel service records.
Features and Equipment
- Standard: Hydraulic shock absorbers, 4-wheel mechanical brakes, sun visor, lockable doors.
- Luxury add-ons: Heater (Thermosyphon), radio prep kit (50 Reichsmarks), whitewall tires.
- Safety: Cyclops third-side indicator (early turn signal precursor), reinforced bumpers.
- Interior: Wool upholstery, adjustable seats, dome light in Spezial models.
Contemporary reviews highlighted the P4's "over-equipped" status; a 1935 Autobahn Revue test called it "the poor man's Mercedes" for refinement at half the price.
"In an era of streamlining, the P4's boxy shape harked back to the 1920s, yet its value proposition made it timeless," observed engineer Fritz von Opel in a 1936 interview.
Production and Legacy
From January 1935 to June 1937, Adam Opel AG in Rüsselsheim built 65,864 P4s across 12 months peak production at 4,000 units monthly. It bridged to the 1936 Kadett, which added independent front suspension. Today, 50-70 survivors exist worldwide, valued at €15,000-€30,000 by collector auctions like Historics at Brooklands in 2025.
| Year | Units Produced | Market Share (Germany) |
|---|---|---|
| 1935 | 37,000 | 12.5% |
| 1936 | 25,000 | 15.2% |
| 1937 | 3,864 | Declining |
The P4 legacy endures in Opel's volume-car DNA, influencing post-war models like the 1953 Olympia. Restorations often retain original 16-inch steel wheels and Zenith carbs, with parts sourced from German specialist firms like Classic Opel Parts GmbH.
Why It Still Matters
In 2026, amid EV dominance, the Opel P4 symbolizes accessible mobility-its 1935 innovation of high-volume, feature-rich economy cars prefigured today's budget EVs like the Citroën ë-C3. Clubs like the Opel Historic Vehicle Register host annual meets, drawing 200+ owners. Vintage appeal shines in films like 1937's Die P4-Reise reenactments.
Stats from a 2025 Hemmings Motor News survey show P4 values up 25% since 2020, driven by millennials seeking "slow car fast" ethos: 85 km/h top speed enforces mindful driving on modern roads.
Expert answers to Opel 4 Specifications Why This Old Car Still Matters queries
Production Variants?
Opel offered four body styles: 2-door sedan (base, 70% of sales), delivery van, cabriolet-sedan, and Spezial-Limousine (upholstered luxury sedan with side-mounted spare wheel and fold-out luggage rack). The Spezial added chrome trim and optional leather luggage, boosting price to 2,250 Reichsmarks.
Why No Separate Trunk?
The P4's name denoted "Personenwagen 4" (4-passenger car), omitting a trunk to minimize cost and length; luggage fit behind rear seats or on optional external racks. This design echoed 1920s norms but sold well, capturing 15% German market share in 1936.
Opel 4 vs. Predecessor?
Compared to the 1931-1934 Opel 1.2 Liter (989 cc, 20 PS), the P4 gained 84 cc displacement, +3 PS, a 4-speed gearbox (vs. 3-speed), and updated styling with flowing fenders, improving sales by 40% amid Depression recovery.
Is the Opel 4 Still Roadworthy?
Yes, with modern upgrades like LED lighting and radial tires, P4s pass TÜV inspections routinely; a 2024 rally event in the Netherlands saw five entrants complete 500 km flawlessly, averaging 75 km/h.
Fuel Efficiency Today?
Restored examples achieve 6-8 L/100 km on premium unleaded (ethanol-free recommended), per federation data from the Opel P4 Register, outperforming some modern microcars in highway economy.
Common Maintenance Issues?
Rust in wheel arches and sills tops the list, followed by kingpin wear; annual costs average €1,200 including valve adjustments every 5,000 km. Kingpins cost €150/pair from repro suppliers.