Originally Posted by
dawesy1700
ive read several articles that state the consumption on LPG is around 30% more than petrol, so if you can find LPG thats around 50% cheaper than petrol, its a saving of 20%
Error in your maths there mate. Based on your numbers (which in my experience are about right with the 30% being for a single point kit, multipoint ones though are often a lot closer to petrol MPG) and based on your price of it being half what petrol is.
0.7 / 0.5 = 1.4
So a journey that would cost you 14 pounds on petrol would cost you 10 pounds on LPG, so its actually 29% cheaper.
If you use a multipoint kit that gets within 10% of the economy of petrol, then you end up with
0.9 / 0.5 = 1.8
Which means each mile will be around 44% cheaper
, so in "theory", a petrol car that does 40mpg on petrol will "seem" to return 48mpg on LPG, but actually doesnt, if you see what i mean?
,
i need a sit down now, hahaha,
As per above, you are incorrect.
A car doing 40mpg on petrol, and based on your figures for lpg would do 40 * 0.7 = 28mpg on LPG
If the LPG is half the price, that would then equate to 28 / 0.5 = 56mph equivalent fuel costs.
And on a multipoint kit giving 90% of the mpg, it would be 40*.9 = 36
36 / 0.5 = 72mpg equiv fuel costs
Hope that helps mate!