Parnelli Bone
You can use a gameshark to make a Rome Night Enduro?
Sure, you just force a track to be used via GS with the right code. I tried a 50-lap Midfield enduro race (code the track, enter the SSR5 All-Night event), and a 30-lap Tahiti Road race (in place of the Trial Mountain event).
If there ever were an improvement on the enduros in the next GT installment, a track randomizer would be my choice.
On topic, I found the "normal" Corvette races to be quite tough. In stock form, none of them are easy to drive. The "normal" Tuscan race wasn't easy without some car modifications. The Elise Trophy is hard; trying to race the AI, who doesn't seem to have the same problems with this particular Lotus, makes it a toughie. Any race at the Test Course is bound to give you fits if you don't buy a full-race tranny.
I've always found the Neon, TT, R34, Civic, and AZ-1 races to be a cinch. I've raced them all plenty of times, never lost them in any one of my games.
The RX-7 and GT-R events are my favorite, for some reason.