Auto Union?

In May 2001 Audi brought several cars to Donington Park to be demonstrated at the Richard Seaman Memorial Trophies meeting and on 2 December 2012 I showed some photographs of the rebuilt Auto Union C-type and D-type cars like those that had competed at Donington Park in 1937 and 1938. The photographs below show one of the other cars which took part in the display in the paddock and the demonstration on the track.

It's a car that was in the Donington Park museum when I visited in May 1989 when I took the photograph below:

I seem to recall that the story of this car in the museum was that it was an Auto Union E-type that the factory had designed to challenge the Mercedes-Benz W165 1½ litre voiturette that had won the 1939 Tripoli Grand Prix, but production of the car had been halted by the Second World War. Tom Wheatcroft was said to have acquired it as a chassis with engine, and a body was designed and built to show how the car would probably have looked had it been completed in 1940. The Auto Union factory ended up in East Germany after the war and all the racing cars and equipment were removed to Russia. There are suggestions that this car is of post-war East German or Russian manufacture, possibly with the help of pre-war Auto Union design technology, but Audi seemed to be sure enough of its Auto Union origins to have included it in this display at Donington Park in 2001, though I can't find any mention of it in the commemorative 'The Return of Auto Union' brochure or the programme of the event. In trying to piece together this story of the car I've come across three interesting websites, on supercars.net, 8w.forix.com and an Autosport forum. I think my recollection of the car may be from a book about the Donington Collection which I bought on one of my visits there, but unfortunately I can't find it at the moment. If I do come across it and it mentions this car I'll update this story.

This is the car on its demonstration run at Donington Park taken from the inside of Coppice Corner.