Chrysler Sebring:
mass = 1520 kg
fuel economy = 30 mpg (gasoline)

FuelVapor Ale:
mass = 635 kg
fuel economy = 92 mpg (gasoline)

Clever Car:
mass = 395 kg
fuel economy = 110 mpg (natural gas)

Testing the Hypothesis:

Compared to the Sebring, the FuelVapor Ale has 0.418-times the mass, and should get 1/0.418 = 2.39-times the fuel econony, or 72 mpg. According to the website the FuelVapor Ale does better than that, getting 92 mpg. Excellent result, possibly due to the claim of an innovative fuel system and low air resistance. Appears to lack rear-view and side mirrors though, and these would be required to be street legal. Great looking vehicle all around, but low-slung and might not have good forward-looking visibility, and it still uses fossil fuel. No tilting mechanism required for cornering stability - one less thing that can go wrong. Top speed is 140 mph, great for freeway speed, and hackers could disable the electronic speed limiter and get even more out of the 180 hp engine! Waaaay outpowered for a car this size, but who cares right? Looks alot like the old Merlin Roadster from Corbin Motors (bankrupt 2003). FuelVapor still looks like one of those small startups with an uncertain future.

The Clever Car has 0.26-times the mass of the Sebring, and should get 1/0.26 = 3.85-times the fuel economy, or 115 mpg. According to the website the Clever Car gets 110 mpg equivalent using natural gas, very close to the expected performance. At the same time, the Clever Car might provide better visibility than the low-slung FuelVapor Ale, but needs a computer-controlled active tilting system for cornering stability. Top speed is only 60 mph, and this might be frustrating for people who like to use freeways (or even the passing lane). BMW is funding the development of this vehicle.