Another favourite, that was featured on 5th or Top Gear some time ago when they were testing a 2 seater, british sports car. Jason Plato stated that it's impossible to do more than 30mph up the hill because of the zig-zag nature of it.
I disagree Mr Plato, I've done more up that hill, with only 3 out of 4 wheels on the ground
(fully attested by Shark_90)