@James
Liquid Natural Gas Hybrids are really the ultimate coming technology, even though Diesel Hybrids are interesting for the moment. Gasoline is just a very poor source of fuel for several reasons.
I'm not sure I would agree because LNG creates too many problems in itself. Now consider the number of accidents that occur and the fact that if any part of the tank and lines rupture a highly combustible pressurized gas is released and when ignited explodes. It is a disaster in the making.
If you consider that the average total conversion efficiency is still well below 20% then we have done anything but well. If you gave me one dollar for fuel and I only gave you 20 cents worth would you consider this money well spent?.
Maybe it's about time we look at the real facts.
As a Power Engineer the first thing we look at is combustion analysis, that is what is in the fuel and how much energy does it have. Generally the carbon reduces to CO2 and the Hydrogen reduces to H2O. As such the best fuel has the highest energy density at which point we come to combustion efficiency. This relates to how much of the Energy is liberated as heat which then produces pressure.
Next we have conversion efficiency which relates to the percentage of Energy which actually performs work versus simply being dissipated into the environment as heat.
You know it's funny how people talk of technology but nobody can argue the fact that a 30 year old volkswagen rabbit diesel using 50+ year old technology still gets better mileage than 90% of the new hybrids with no batteries required.
As well the real problem with these micro-diesels has nothing to do with efficiency. It was the fact that the mighty rabbit could go almost 500,000k with almost no maintenance other than changing the tires and oil. Thus the auto-makers were losing money because it is a well known fact that most sell the vehicles near cost and profit from parts and labor. This is the reason new vehicles are so complicated because almost no maintenance can be performerd by the owner. It has nothing to do with efficiency because the parts and labor will always exceed the savings in fuel...catch 22, your simply paying the auto maker instead of the fuel producer.
In any case as an Engineer I can tell you that we have no problems with engineering a simple 100 mpg diesel car however the economics will not allow it.
AC