It’s a bit like comparing a carburetor with fuel-injection. A carburetor is really a compromise and is very difficult to tune perfectly for all running conditions, so there is often a problem where the engine coughs, splutters, misfires, stalls or surges. Electronically-controlled fuel-injection can be more precisely tuned to all running conditions, whether it’s hot, cold, wet, windy, high speed, low speed, whatever. The end result is that the car performs better and gives better economy. It’s the same with the vapour-injection system; your car will run better, it won’t stall, stumble, surge, and the performance will be the same as it would be on petrol. Whether that makes it worth the extra $1900 or so it would cost is only a question you could answer. For me it is, I wouldn’t be bothered with an old air-valves system, which is the cheaper system you would be getting.