In 1951 the twin seater cabriolet-saloon Champion 400 was presented with a full width canvas roof reminiscent of the open-topped Fiat Topolino though in other respects the overall architecture of the design remained closer to Wolfsburg than to Turin. The steel bodied car was reported to be notably more solidly constructed and the suspension had gained both in sophistication and in terms of ride comfort. The weight of the car was now virtually doubled as against the original 250 model, to 520 kg, and road-holding on the corners became more challenging.

Power came from a with a two-cylinder 398 cc ILO engine. Output was now given as 14 PS, and the maximum speed increased to 80/85 km/h (50/53 mph). Between 1951 and 1952 around 2,000 were produced. However, the car no longer occupied the price niche of its predecessor, the price having increased by the start of 1951 to DM 4,300, which almost matched the price of the Volkswagen Beetle, which had itself recently undergone a substantial price reduction supported by increasing production and sales volumes.

After Champion production moved south from Paderborn to the Hennhöfer plant at Ludwigshafen the original Champion business collapsed. The Ludwigshafen Hennhöfer company which was by now assembling the cars on behalf of Champion nevertheless committed to persist in producing the cars. The engine was switched to a 16 PS Heinkel unit, and the model name was changed from 400 to 400 H. Roughly a further 1,941 of the cars were built in Ludwigshafen on this basis before Hennhöfer, in its turn, collapsed in 1953.

The Danish entrepreneur Thorndahl struggled to revive the business in 1953/54. Under his watch 1953 saw the introduction of the Champion 500G, an estate version of the car with a steel-timber body and a 452 cc Heinkel 18 PS engine. However, only 20 of the 500G models were produced, and in total output under Thorndahl amounted only to 300 vehicles.