As the war progressed, military authorities placed greater stress on the development of air-cooled engines, which they felt had more immunity to damage from weather, shellfire, and misuse. To meet this demand, Opel engineers developed an unusual variation on normal cooling for the 3.6 L truck engine. It was called "air-oil cooling", and used engine oil to take heat away from the jackets around the cylinder barrels. The heads were directly cooled by air, there being three separate aluminium finned heads, each serving two cylinders. Of this interesting engine, which developed 72 hp (54 kW; 73 PS) at 3,000 rpm on 74-octane fuel, only three examples were built.
The transfer gearbox in the AWD models — the same as used in the Vauxhall Cavalier AWD—was somewhat on the flimsy side, liable to suffer damage from conditions such as minor differences in tyre wear or tyre pressure between front and rear axles. Since front and rear tyres would naturally wear at different rates in normal driving, it was necessary to swap front with rear tyres every 15,000 miles (24,000 km).
The Kadett A (above) finally appeared in 1962, and was a classic GM/Opel effort: highly pragmatic, conventional in every respect, reasonably stylish for its time, and designed to deliver a good bang for the buck. In just about every way possible, it was the antithesis of the VW: front-engine rwd, a rather tinny but roomy body, highly tossable but with a primitive suspension and ride, a very roomy trunk, and excellent visibility as well as economy. Oh, and a proper heater even! Its little 987 cc OHV four made 40 net/46 gross hp, six more than the VW 1200. Its trim fighting weight of 1475 lbs (670 kg), some two hundred pounds less than the VW, showed in both its acceleration and body integrity.