Nannarose
Have you checked the insurance? If you insure a car for another person, there are sometimes conditions in the small print about what constitutes 'occasional use'.
If she is driving on her 'own insurance' you may find it isn't full cover - I would ask her to check.
I would also consider ( adding to GagaJo's idea) something like 'we don't want to get rid of the car, but we do need to keep costs down, so it's only insured for the 2 of us'.
Another one would be 'I'm a bit unhappy about the clutch / brake / overhead gasket and I'm trying to book it to be looked at'. You could then add that 'if it turns out to be a big repair, we'll be getting rid of it'.
I assume that you are actually in the middle of a marital disagreement - she really wants a car, and her husband doesn't see why! Does he know she borrows it this often?
To be honest, I don't know if she is insured to drive it or not.
There is an intermittent fault on the car which I think could be quite an expensive fix.
Her husband is aware that she is borrowing the car.
Unfortunately, I am a rotten liar and not very good at saying no.
Personally, I think that if she wanted to use their car and her husband is working, she should take him to work and pick him up. He works about half an hour away from their home

