Is this the one in the professional hall? If it is, use the Toyota 7 if you want to B-Spec it, assuming you won't A-spec it. Because you could probably win in A-spec with any car... like the Mini, I think that's what I used.
I'd recommend the Nardo, but you can't get it until the Extreme Hall. The Cadillac Cien should be alright (you'll need to win an "easy" tarmac rally), but I recommend the Mercedes SLR McLaren. You'll pull about 50 points per race with it, but it's actually a suprising challenge even at that.
But be aware of the SLR's gearbox, while you'll be going over 200km/h with it (don't know conversion for miles), you'll still only be in fourth gear. Plus, the brakes leave a lot to be desired - I cannoned into the wall at the Broadway Complex (my name for Turns 1 and 2 of NYC - I HATE refering to corners with numbers ...) six times out of six laps becuase I didn't brake enough and though the HUD said I was in 2nd, I was still doing 120km/h within 50 metres of the actual corner.
There is a way around the "stock" regulation (ie no modifications), but I'm not going to tell you.
I don't think the Ginetta brakes at all does it - it stops purely by air resistance...
But I still love it.
I completed the Compact Car Cup with a '76(?) VW Golf GTi (the first one anyway). Have a look at the "Stock car comparison/challenge" thread, my race is in there. I can't remember the points I got, but it weren't hard in that car.
Do you race?
There is a way around the "stock" regulation (ie no modifications), but I'm not going to tell you.