Problem with Vehicle Collection

The cars in the below linked pack are supposed to be drivable, but I can’t see them in the “Vehicles” menu. However I looked in “Browse” and could see the prop models for all of them. Any idea what the problem might be?

This maybe because those are Gmod 9 cars, and aren’t compatible with Gmod 10. I could be wrong, though. I’m still learning.

Like I said, I can still see the prop models for the cars, so that probably isn’t it.

Like I said, I could be wrong. It’s hard to determine if it’s a GMod 9 addon.