Yes, I understand what you're after, but really, cars never break down in Sims 2. That is the reason there is no mod out there to allow your Sims to repair their cars like you described.
Cars just never break down in Sims 2 unlike the bathroom and kitchen fixtures and electronic devices. EA didn't think broken down cars would appeal to the general audience or a good selling point to generate more $$$$ for their pockets by selling an EP with cars that break down like the toilets and shower stalls.

That's the closest I can think of that will more or less satisfy what you're looking for. But someone will definitely look out for more stuff and come along to pass the information on in here.
