That is why I think we need to do things incrementally.
I think natural gas vehicles can be a bridge to later new technology, if nothing else, get us off foreign oil.
Diesels are big in Germany, but why not here, 20% better fuel economy right off the bat.
Hybrids are OK, but why not flywheel energy storage. Sure it only gives about 20% at best, but it is 20% increase in fuel economy and it is far cheaper than Hybrids.
In 200 years hydrogen gas will probably replace natural gas in the same pipeline systems. Steel wool pads have to be installed on gas burners because hydrogen burns clear, not blue like natural gas. The steel wool glows red to show it is burning. Then the compressed hydrogen could easily replace compressed natural gas for vehicles. Or you could make hydrogen fuel cells.
Our energy problem(s) are not how electricity is made, but transportation fuel, which is imported. We use coal, nuclear, hydro, wind, solar, and natural gas to make electricity now. None of which is imported. With anything imported our money leaves the country and may never return. Whatever is produced here, the money stays here creating jobs. Whether it be fuel or manufactured goods. Drilling, installing pipelines, installing nuclear power plants, etc, creates good paying jobs here, and the money is spent here.
Haven't heard about it lately, but Volvo was working on a turbine engine about the size of a lunch box. It could run on any fuel, diesel, gasoline, natural gas, propane, or alcohol. It ran a generator which charged several batteries. The batteries were standard deep cycle marine batteries. The vehicle was powered by electric motors one in front and one in back. The small turbine powered the front motor, and while the car idled, it charged batteries which ran the rear motor in acceleration. The car it was installed in was a standard full sized Volvo. It got 50 mpg. The same car with a standard gasoline engine only got in the low 20's mpg. The small turbine was cheaper to manufacture than a large turbine. They said this might come on the market in a few years. A truck or large SUV might have two of these turbines. Turbines are far more efficient than piston engines, but are more expensive to manufacture. Being smaller helps.
Another thing I heard, was Chrysler was making an all plastic 5 passenger hatchback car in Brazil. This car used a twin cylinder garden tractor engine. Doors had metal pins and hinges. Metal inserts were placed in high stress areas like axles to the frame or bottom engine mounts, etc. This car had no heater (Brazil doesn't get cold). It also had no air condition. This car was to be sold for around $6,000 new. It got 75 mpg. It was not going to be sold in America because of safety concerns.
So, any incremental improvements helps. Turbines, flywheels, better and cheaper batteries.