"Test Course's italian cousin shares its name with a car. That car shares engine type with another car (which is not in GT). That car's name is identical to my name"
In case anyone was ever in doubt, that's the right country.. But it's not the manufacturer
Allow me to remind you of how this is put together:
We're looking for a car that shares name with a car with the same(-ish) engine as the one used in the car (made by the same manufacturer as the car with a similar engine..) that shares name with Test Course's italian cousin.
It doesn't get much more simple, apart from the final answer
Test Course is a course built for testing top speed. It's italian counsin would be the Nardó Ring, which shares name with the Volkswagen Nardo concept vehicle, which is powered by a W12 engine (2 V6's combined). Is a W12 used in other VW's? Yes, for example the top level of the Phaeton ('10-'11 model years). Isn't the rest pretty obvious from here, seeing as the only connection we're missing is that the car I was looking for and the car that held part of the riddle also shared names?