As a rule, the first missing element in the first format would be something which really is undecided/unknown at the time...
Even if win the lottery, I probably won't be able to buy Buckingham Palace
In the second sentence, the missing element would normally be something already postulated to be true (by the speaker, but not necessarily accepted as such by the person being addressed)...
Even if I am stronger than you, I probably can't beat you in a boxing ring
In that second sentence, even if really means even though. It's a common way of phrasing such statements.
Per kiamlaluno's comment, the difference between can't and won't be able to is covered elsewhere. This answer addresses the different meanings of Even if... But to answer OP's question as posed, the sentence is non-standard. It should be...
Even if I find the keys, I probably won't be able to start the car
...because the underlying form is that of my first example.