GT3 cars are built to a spec so if you could take an Escort and do a bit, OK a lot, of re-engineering you could in theory create a GT3
like car out of it. But in reality you're right, probably not*. But that's the beauty of games, in our un-reality things like this are possible. However not to everyone's liking of course. I'm undecided whether to embrace it or not, I'm warming to the idea though.
*There are some really rapid Mk1s, especially time attack and hill climb versions. Too late to buy
this one.