Get An Older Car And Get Lpg?

Hi,

I was just about to plump for a new (or newly new) Honda Civic when the GF pointed out the following: "why not get a slightly older car and get it fitted with LPG?"

Not entirely illogical really. The same cash that I'd spend on a civic (about 900k baht) could instead could get me a slighty older 3.0 V6 Accord.

However, I am worried about that particular model being a 'gas guzzler', but would love to get my hands on the V6!

So, will the older, thirstier, more luxurious Accord be cheaper to run than a smaller 1.8/2.0 Civic ran on petrol?

(Honda void your warranty if you convert a new car to LPG, hence the reason we'd do it to an older model)

Any ideas/thoughts?

Cheers

James