[euromodder]

See how much diesel you can replace with LPG

Calculate
What the £ savings in unused Diesel are over 100miles
minus
What the extra LPG costs for 100 miles


You know how many miles you do/year
That gives you your savings/year

Then see what the installation would cost
Divide by the savings/year and you know when you'll start making a profit ...
Gonna be a while I'd think


LPG tanks will be cheaper (lower pressure) than CNG
You'll normally need an extra MOT after installation
Probably extra periodic tests as well under EU regulation R110