I'm too OCD for mods, just the thought of having cars of (great) different visual and sound quality is enough to make me sick. That is another reason why I left the GT series (standard, premium, crap sound, good sound, etc.) pCARS will perhaps ship with less than a 100 cars and I couldn't care less. There will be a great deal of consistency in the modelling throughout all cars and that to me is far more important than the sheer number of them.
Also Project CARS does not have many cars if you compare it to GT or Forza but both those games' car count is ridiculous. In reality it does have a lot of cars, it has 70+ I think (I never checked the car list ) which is a huge number. Most people in their lifetime will own about 4, 5 cars (stat out of my ass). The important thing is how you pair those cars. In GT and Forza you have these grids which make no sense. In a race you can have a Tank Car next to an Odyssey van and a 500bhp concept car which is stupid. I rather have a selection of only 40 cars where from that pool you get say two dozen disciplines/series.