Rocka covered it.
The readme should have been a good place to look to begin with, as it mentions both the spawning function and the remember car ('spoosh' if you prefer) function.
I know its a hassle that not everything was open to begin with, there are a few things I didn't get around to unlocking from the start. If I find myself working on a future version, and can be bothered, I'll try to unlock more of the stuff. But yeah, the reason I didn't do a savegame for it is because I'd have to do 3 seperate ones, and if I ever made an update they'd probably be wasted.