If I understand correctly: your opinion is that it will all happen in the car?
I think it's dangerous in the car, unless he parks the car at the driveway in which case Liam has nowhere else to park.
Let's not forget that Liam can show up at any time.
My Opinion: I'd say it will happen in the backyard and Sam will jump the fence again. And when Liam shows up I hope Sam hides somewhere in the dark.
It would be interesting if L&P also introduced Dylan, he hears/sees his mother going to the backyard(this is where the cockold route points appear) and follows her. Last Liam appears but sees no one.
Somewhere, sooner or later Sophia has to figure out that Dylan has a fetish, whatever it is: cockold/voyeur