How about having AVUS as a cycling proving ground? The North Curve is alive, so just tunnel past the left side of the bend until you have a good amount of straightaway (7 miles would be enough), then recreate the South Curve and come back out on the right side.

Here's how the North bend back then.


Just pave the Curve with smooth blacktop and every other section and voila! Now the only problem is where to put the new paddock.