What's the problem you were trying to solve?
Do a significant portion of bochurim not have family or friends they can borrow from?
Are guys just too embarrassed to ask?
Regardless, it sounds like a good idea in theory but I feel like you'd probably have a hard time finding enough people willing to lend out their cars to strangers...
Most bochrim (at least my friends) didn't have who to ask and ended up renting most of the time. It was really starting to add up and it would take a whole day of headspace being hopefull the car would be there (or need to leave work early to go pick up a car from a more reputable rental place).
The idea of the gemach really started when a friend who wasn't really interested in a second date refused to go out again even though she really wanted to simply because it was very expensive and he felt it was a waste of money as well as a headache dealing with renting and parking etc.
He agreed that if money wasn't an issue he would be willing to go on a second date (although he still felt it was a waste of time and headache) .
So from there we started thinking of ways to alleviate these problems.
The idea was getting some people who have cars with garages who usually don't need their car during the evening hours lend out their cars for bochrim to date.
At the end we all just moved on in life and unfortunately it never panned out. Although I still think (once logistics are worked out) it's a great idea for a gemach and would really help bochrim in this regard.