Wish / If only ...

I wish I had a car.

We use wish + past simple to talk about things we would like to be different in the present / future (but which are impossible or unlikely).

I wish my neighbour would stop making noises.

We use wish + person / thing + would to talk about things we want to happen, or stop happening because they annoy us.

I wish I had studied harder.

We use wish + past perfect to talk about things that happened or didn’t happen in the past and which you now regret.

SWAN, Michael. 1998. Practical English Usage. 2^nd ed. Oxford: Oxford University Press.

Wish and If only