It sounds like this is your first time through the game, Bill.
If I remember correctly, the Beetle Cup gives you a quest.
The one thing that the Beetle Cup series forces you to learn is how to modify your car, to keep pace or out pace the AI cars, on the Test Course. It's a one AI car race, with all Cup cars. The stock car can't win the race. Trust me, I just tried five times, making small changes as I go, to see what it took to win again. This was the last race of this whole level that I couldn't just buy my win (by getting more horses, etc).
You can pass the AI at the start, but they just sit behind you, taunting. Then they pass you and you go "cough, cough", but can't catch, draft or block them. Then they stay in front of you, taunting you again! No win.
You need to find the minimum of changes that allow you to win. The only "nice" thing about this race is that you are still paid to come in last.
People hate the Test Course because it is so boring, but it can teach you a lot about different things.
Good luck,
MasterGT