I have won this race several times in B-spec, beating the Huayra, with the Lotus Elise '11. And I'm still working to improve the results.
Edit: Now have won against all top opponents. Best lap 1:19.702.
2nd edit: That 19.702 must be some kind of fluke due to drafting. After numerous additional runs, I have been unable to replicate it. The closest I'm getting 20.2's and 20.3's and 20.4's.
However, the wins against any combination of opposition at Willow are there, and come automatically without any additional instructions to B-Spec Bob during the race.
At Ascari, the other Super tire wear and fuel mileage event for normal cars, I can win against any opposition, but I'm running 4-14 liters short on making it a full run without a pit-stop, so Bob makes a late stop to top up and loses. To win, I must instruct him to stop at lap 5. If he does that, he wins because he never slows down on worn tires. I've noticed he slows when the tires get down to below"5".
Note: At Willow I can Push it Hard! But at Ascari there are many wrecks resulting from this, so it's best to Push the Pace at Ascari.