Originally Posted by mwiener2
How big and where are you putting the propane tank? How crash safe are you expecting this to be?
Propane tank conversions are very popular in europe. Over in Serbia it seems like 50% of the cars are on propane there. It's about 50% cheaper which is the driver over there, especially when you're looking at $1.50/L (almost $6/gal on much lower monthly income than the US), so it's hugely popular. I've driven propane cars that have the propane tank, and in the event you run out of propane, you can switch to gasoline. The only difference is that under gasoline power the car is a bit quicker and peppier, and is slightly more fuel efficient. I would believe that if the car was designed to run on propane from the start you could get it to be just as fuel efficient, and just as quick as a regularly fueled car. The slight drop in mpg's still makes the propane conversion worth it over there because the propane is so much cheaper that they still come out ahead.
As for safety, they have their accidents over there just like anywhere else and I've never heard of a vehicle exploding or the propane making an accident into something worse. Most likely in an accident, either the tank is not damaged or if it is, you just have propane vent out.