Don't buy the McLaren F1. Very shit car. I do not recommend it at all and I feel like anyone who buys it is a knobhead. Note, I am definetly not trying to prevent people from buying a McLaren F1 for my own benefits. I just don't want it end up like the P1. Also, ignore my avatar please.
Rather than buying cars and reaching the end game, try having some fun; splash out on some guns and rob the bank. Try out something fun because most people get bored when they have a fast car and a load of cash.