Veyron should beat a Mclaren F1 around daytona. Veyrons can actually turn pretty decent and they have massive ammounts of traction, but yes the speed comes in the straights and the lighter cars have an advantage in corners, but Daytona is not corners in the traditional sense ^^. On the top gear test track i was running almost a second faster with the Mclaren F1 than i was in the Veyron (both standard). In its power range the Mclaren F1 is the fastest road car around a track, Veyron is the fastest where it can take advantage of top speed.
Should be said tho that the Mclaren F1 can keep up on the straights in a draft (probably other cars too), due to how over the top unrealistic the drafting is in GT5, drafting provides an absolutely massive performance boost and the F1 has the gearing to keep up with it all the way, so could compete in a race at La sarth, assuming it can stay close enough to the Veyron to stay in draft range.
These are the top speed times i logged a while ago at SSR7 for standard cars. (Missing a few, but will give you an idea)
Bugatti Veyron 16.4 '09 @1007Bhp - 242Mph
Pagani Zonda R '09 @753Bhp - 225Mph*
Mclaren F1 Road '94 @657Bhp - 223MPH
Chevrolet Corvette ZR-1 (C6) 09' @652Bhp - 219Mph
Ford GT '06 @ 561Bhp - 215mph
Top speed difference in the Veyron may not be enough to allow it to pull away from a drafting car. Though the Veyron is hardly slow in the corners either, and acceleration wise it will beat all the above.