I think the BMW was faster in the corners but slower on the straights.
That's how the BMWs and Datsun 510's kept up in Trans-Am. They couldn't hang with the faster 5.0 liter cars, but the quickest ones were nimble enough to run with the mid-pack V8 cars. In the vintage races I watched over the weekends, several BMW 2002's were keeping up with the back of the lead pack and well ahead of a large number of V8 cars.