You can save Rusty's car anyway. I did in the one route I took the VIP pass and had 54 $ to spare after paying for the windows. I usually end up having 50-60 $ left after paying for the windows (I'm still a bit annoyed that you don't get at least a bonus for it in the party planing), not counting the 10 $ you get for the VIP pass.
I'm curious, has anybody here actually failed the mansion restoration minigame?
Wait, you are talking about accepting the VIP pass
with minigames on, right?
I've read many times on this forum that if you play
with minigames off (and thus you don't have to play mansion restoration, so you don't have the "mansion money"), if you decline the VIP pass rusty's car is saved, while if you accept the VIP pass Rusty sells his car.
I've never played with mini-games turned off, and I haven't checked the code, so I can't 100% vouch for it. However, it has been stated on this forum so many times by different players that I'm quite confident that's how it works if you play with mini-games disabled.