[beachboy]

If I had had money, I would've bought a car. I didn't have money, so I didn't (couldn't) buy a car.
When the situation is past, wish is not a problem for me. The problem arises when it comes to present (verb in the past)
If I had a car, I'd drive every day (but I don't have a car, so I can't drive every day).
If I bought a car, I'd drive every day (but I can't buy a car, so I can't drive every day).
I just don't know how to explain that, while I say I wish I had a car, referring to the first sentence, I say I wish I could buy (and not bought) in the second one.