LPG car coversion. anyone here?

Hi. Most of what you have been told already is correct.
Yes the government used to pay towards the conversion costs with a grant through "powershift" but they stoped about 18months ago. I would recommend it, having run my ML now for over 6months after conversion. The economics would mean keeping the car for at least two years. I opted to buy a ML350 rather than the more common (in the uk) ML270 diesel basicaly because the petrol ML's are usually cheaper than the diesel version and in my case the saving i made by buying petrol version paid for the LPG conversion, secondly the diesels usually have much higher miles on them when sold secondhand. I got a two year old ML350 with only 14,000 miles, most ML270's had alredy done around 25-30,000miles.
I get an average of 21mpg on the car running petrol, on LPG it would be around 19mpg as the gas has less calorific value. I buy LPG for 40.3 pence per lliter and petrol at 94.9 per liter. Working all the sums back its like running a diesel returning 35mpg.
The conversion is totally stand alone, all the original petrol tank, injectors, pipes and electronics remain with additional gas injectors, pipes, tank and ECU added. The tank is fitted where the original spare wheel went, under the rear floor. I fitted the external wheel carrier. The tank is 55ltr but can only be filled to 45ltr. There are much bigger tanks available but they would have to fitted in the rear behind the seats. I need to fill up with LPG every 170 mile roughly, and as not all garages are selling the stuff it needs some planning. But as it will just change back automaticaly to petrol when the LPG runs out its no big deal. The road tax is also changed to the alternative fuel class and comes about £10.00 a year cheaper.
The car performs just as well and is almost impossible to tell if its on petrol or LPG. As i planned on keeping the for at least 3 years i am very happy with the savings on running costs.
Given your vehicle age and how long you would need to keep it for I don't feel it's viable.
Hope that helps.

To fill my tank with 45 liter it takes about 2, 3 minutes.

About the cost. I just calculated the next. (this is all if you live in Holland like me)

Lets say I drive 20000 km a year

Patrol= with 1liter I can do 7.5 kilometers that means that I spend for 20.000 km

20.000/7.5= 2666 liter , a liter cost around 1.45 euros so I pay 3865euros a year.

With LPG I can do 6.5 kilometers whit 1 liter, so for 20000K I use
20.000/6.5= 3077 liters , lier cost at this moment 0.45 euros so in total I pay 1384 euros.

So I save just bij using LPG 3865-1384 = 2781 euro's

Of course I pay extra money to the gouvermant because I drive LPG.
Using patrol I pay 904 euros a year, with LPG I pay 1408 a year. That means that I have to pay 504 a yera extra.

So first I gain 2781 euros', but pay 504 extra. That means 2781-504= 2277. Still gaining money

And last the system. It cost me a total of 2250 euro's.

That means that after a year of driving I paid my system ( 2277- 2250=27). And still gain meney (27 euro's)

So just on the second year I am already gaining money by just driving on LPG.

2277 euro's, That is a total of 2861 US DOLLARS .

I hope this is clear why I transform my car to LPG.