Your figures are from CURRENT model availability which is evidence of LACK thereof.
A larger supply of small and efficient diesels would drive down the price of those vehicles. Fully a third of the European private car fleet is diesel powered and successfully so, I might add, with more and more choices coming on line every year in the small car category.
How do THEY manage it?

Furthermore, let me cite the plumbing industry, which has embraced one particular model, the "Sprinter". The switch from the heavy gasoline powered service pickups and vans to the Sprinter has leveraged a very significant savings to local plumbers all over the USA....and this is just one industry, one model vehicle, and this vehicle is large but equipped with a SMALL (3.0 liter) engine.

I'm with you, small diesels are great. We have one in a backhoe that will run for days on 10 gal doing trenching. My nephew has a diesel powered arc welder on his truck that is the same.

Canada had a lot of LPG gasoline conversions 10 years ago. It was substantially cheaper at that time. The demand for LPG went up and so did the retail price and now it no longer makes sense to do the conversion. Supposedly not putting butane into summer gas makes it more expensive, but they are selling the butane in LPG for as much as summer gas.

Anything that is cheap for the consumer at the moment, whether it's corn or cellulose for an ethanol plant, silicon for PV or a consumer fuel is only cheap until demand increases. That's capitalism and why I believe the solar thermal is the only way out of the energy mess. You can't come up with a scheme that relies on something that is cheap now, it won't stay that way when demand increases.

Ethanol production increases and corn went from $2 to $4/bu. and will hit $5/bu. D'oh! Ethanol guys never saw that coming. Let's build a cellulosic ethanol from straw/stover plant.. woops they don't want to give us biomass for free. Let's convert passenger vehicles to diesel, NG, LPG or anything else...

Darn. The price went up with demand. As Mr. Young put it:
Keep on rockin' in the free world.