Stupidest idea ever

The Zipcar du jour was Eva, a Ford Escape living in the Alewife garage. This is a vehicle whose rear-view mirror doesn't allow you so much to see the cars behind you as to see over the cars behind you, a vehicle with the general aerodynamic properties of a Borg Cube. It was, I'll grant, a fairly comfortable ride, particularly through the questionable pavement of Harvard Square. But the negative-zero-emissions-vehicle aspect of it seems contrary to the Zipcar environmental bit. Given that these are expensive vehicles, that are expensive to operate, they're kind of dangerous (both in the "roll over" and the "greater risk of putting your bumper through someone else's windshield" senses), why are SUVs so popular?