You can't argue CG's experience in PPC. They have basically built their traffic on it.
The question is: Would they do as good of a job with a website they don't control, also buying for new car.
Buying PPC for new car is much different from P/O.
You have to make sure it's tracked correctly and objectives are set clear before starting.
Can you provide more info on your end (website, brand, approx market)?