My roommate sent me this picture of the rental he and his girlfriend are using in LA. I honestly didn't even remember they built this thing. Probably because I barely ever rent cars. It's a grey, automatic crossover. I think it has to be the most forgettable car ever made.
It's an interesting question, because you can't just pick boring cars. Nobody can forget about the Camry or the Malibu because there are so many. What's the car that came and went without you ever noticing?