Instead of would here it is possible to use could (ability or possibility), should (obligation) or might (possibility).

George could have won the race if his shoelace hadn’t come undone.

Compare these two sentences:

In the case of present and future the concept of possibility is more or less the same as that of certainty/uncertainty, which is discussed on the page Modals expressing present and future certainty/uncertainty.

I could have given you a lift.

This sentence is an offer only in theory. In practice it expresses possibility. Note that this is the main clauseA clause that could be a sentence in itself. E.g.: I wouldn’t go there if I were you. ("I wouldn't go there") When I arrived he was surfing. ("he was surfing") of a third conditional sentence.