> there's no reason to suppose that 10 years from now that guy won't be able to haul a dead deer in an SUV-sized vehicle that does 50mpg.
Increasing the fuel efficiency of vehicles is not something that can be achieved by will alone; it also requires the cooperation of physics.
First, the SUV could quite likely already do 50mpg if driven by a hypermiler, and maybe fitted with truck tires and a streamlining tail. But it would take twice as long to get back from the deer hunt, and it would be a bumpier and much less comfortable ride.
At a given speed with a given frontal area in a given density of air, though, you're really limited by how low you can get the drag coefficient, and at any speed you're limited by how low you can get the mass and rolling resistance.
Increasing the fuel efficiency of vehicles is not something that can be achieved by will alone; it also requires the cooperation of physics.
First, the SUV could quite likely already do 50mpg if driven by a hypermiler, and maybe fitted with truck tires and a streamlining tail. But it would take twice as long to get back from the deer hunt, and it would be a bumpier and much less comfortable ride.
At a given speed with a given frontal area in a given density of air, though, you're really limited by how low you can get the drag coefficient, and at any speed you're limited by how low you can get the mass and rolling resistance.
On this subject, I highly recommend Chapter A, "Cars II", of Sustainable Energy Without The Hot Air: http://www.inference.phy.cam.ac.uk/sustainable/book/tex/ps/2...