Hi again John !
Having personnaly run a Toyota on LPG I think it is important to give attention to the drawbacks of the system and be aware of them.
- Extremely cheap ! (by order of prices, cheaper first) : Belgium, Netherlands, Italy, France, UK. Not available (or almost not) in Spain and Germany.
- Very ecological
- Whatever people say it makes your car less powerful(+/- 10% less power)
- Fuel not available everywhere (however you can switch to petrol or LPG by just pushing a button on your dashboard)
- LPG being very dry it tends to ruin valves and valve seats very quickly especially on most Japanese cars. You can however use a system called "Flashlube - valve saver" that injects an additive directly in your intake manifold (cost +/- 40 GBP). I would highly suggest to use this.
- huge tank in your trunk
- Not too much autonomy on LPG (generally +/- 300 miles)
- Consumption by +/- 15% higher
- Many mechanics feel completely lost when they see an LPG installation.
- Really expensive to install. Expect at least 20,000 miles before making it profitable.
Stereotypes about LPG :
- "Dangerous" : seeing all the safety characteristics brought to the system (distortionable tank, blow off valve,...) the system is actually safer... than a petrol tank !
All in all I think the system is interesting especially for big engines like V8's,...