lol, I was confused too, but I just didn't ask.
I suppose muscle car is being referred to twins and since supra is an inline 6, it could be referred to inline bikes. however, I don't see how it could be analogous to bikes. good muscle cars run about 12 secs stock or minor mods, while twin turbo supra run about 13s. where as 4 cylinder bikes are faster than an equally displaced twin.