With gasoline pushing $.00/gallon, does it make sense to convert a car to run on LNG? The conversion costs about $2300.00, and you lose your trunk. Still, we have lots of LNG-and the stuff actually makes the car run cleaner. Does it make sense to convert?
Something like 15 years ago I worked on a project to develop a car that ran on compressed natural gas. The two major problems were:
infrastructure – unless you had natural gas service at your house and installed a special compressor/pump, you were pretty much out of luck when it came to filling up
range – CNG didn’t hold near the energy that an equivalent volume of gasoline or diesel would, so the range of the car was limited by the size of the tank.
I don’t know how LNG compares with CNG for density, or how you’re going to refill your tank. The car will run well, but you’d better have the details worked out for your situation.
You also can no longer park in most underground parkades.
I’ve not used LPG, but I ran CNG for many years in NZ. LPG has a much higher energy density than CNG, so your mileage is similar to a tank of petrol (but not diesel). People often have a LPG donut tank put in the spare wheel well, or have the petrol tank replaced with a small starter tank and the LPG tank put there.
NZ had a great network of CNG stations, so the reduced range was not such an issue. Unfortunately, more efficient petrol engines (and the cost of conversion) has seen the use of CNG decline, and the network is getting smaller as stations remove the filling points.
As for the OP, LPG is a really good option. Modern LPG cylinders can be made of lighter, stronger materials, the difference in power is only a few percent, and if you don’t need the boot (trunk) space, it is an ecofriendly option.
In fact, I was talking to a friend in the refining industry, and he told me that a new option was shipping LPG from the Middle East. The tanks for that operation are not pressurised, but are thinwalled insulated tanks (about a foot of foam) that are chilled by evaporative boiling. The outgassed LPG is chilled and compressed and pumped back in.
Si
Nothing really to add but I have good memories of happily running my Ford Cortina on CNG for several years in the 1980’s. I worked for Auckland Gas Company for a while and we got great staff rates on CNG. I heard a story that one of the sales people seemed to using much more CNG in his company car than he should have been. It was discovered that he was hooking it up to his house at night to run his stove or home heating or something. 
Why not?
I believe that at least one of the automotive fuel gases, I’m not sure which one, is heavier than air and will pool in low points. If a tank leaks or is ruptured, the gas will flow downward and can be ignited by unsuspecting people far from the source.
I’m not disputing your claim, but I had thought that gasoline vapor was also heavier than air. The reason I say that is that most older houses that I know of where the water heater is located in an attached garage have the heater mounted above 4 feet from the floor. Someone told me that it was done to keep the ignition source away from gas fumes should someone spill a small amount of gas from a lawnmower or something.
It could just be that the heater was located higher for space, so I could be wrong.