I have to agree to Kiyaku here. You don't consider it very bad. To me this means that you consider it bad but not very bad.

Why are you working with a bad tool? Don't punish yourself!

In my case I am indeed happy because it saved me so much time.

And about your car physics. I remember this forum thread where they wanted to collect money for a professional AAA car component (they compared it with GTA IV).
But they also posted tons of existing Unity car demos from users and I found it crazy. I played them for quite some time. I did not see in any other engine so much car games. So it must be somewhat easier than in other tools.