Just wondering why Is almost always the one character who tops who has and drives the car?

Using that BDE to make that money and get that car.

bc it's their car...? maybe they really like picking up and dropping off their partners so that they can spend some time together o>_<o

Because BL enforces the toxic idea that the top is masculine whereas the bottom is feminine. And in real life when it comes to heterosexual couples, usuall y the man drives while the woman sits in the passeger seat.
So they're just copying that dynamic.