Opel P4

In September 1935 the Opel P4 replaced the Opel 1.2-litre. The body was unchanged apart from an updated front grill. Also unchanged were the wheelbase and the transmission. What was new was the engine, which was less “undersquare” than before, though its essential architecture as a four cylinder in-line side-valve unit was familiar enough. The claimed maximum power output and top speed were unchanged at 23 PS (17 kW; 23 hp) and 85 km/h (53 mph) respectively. What did change was the engine size, now reduced to 1073cc. In view of the price reduction from 1,850 Marks to 1,650 Marks which accompanied the change to the P4 model, and the further reduction to 1,450 Marks in 1937, it seems likely that the new power unit was cheaper to produce than the earlier power-plant.

This was also the point at which four wheel brakes replaced the earlier braking system which had operated on the drive shaft.

Despite the unchanged performance, in the marketplace the reduced engine size would have distanced the car from the more modern Opel 1.3-litre introduced in 1934, and from the manufacturer's important new Olympia and Kadett models which entered production respectively in 1935 and late 1936.

 Opel P4 in Netherlands East Indies family

Sources:

http://en.wikipedia.org/wiki/Opel_1.2_litre#1935_Opel_P4