We hear a lot about how engine downsizing and turbocharging is going to give a future with vastly improved fuel economy, all without any sacrifice in power. So the McLaren Mp4-12C, with its relatively small displacement V8 and twin turbos, must be a real fuel saver when compared to supercars sporting great big V12s, right? Well, maybe not, as the following video will demonstrate, the car is still capable of burning quite a bit of fuel quickly.

We get an inside shot of the car as it charges through a tunnel, emerging from the other side lighter to the tune of 5 miles worth of fuel.