doing our bit

[mrsflibble]

my husband commuttes to work by car- he has to because of the shifts he does. anyway, we want to change our rover to make it more economical and more friendly to the earth.

we have considered LPG and a complete engine change to a diesel.

which is easier? which is cheaper? which would cause me not to lose my husband for a month while he does the work himself?!

[Muddypause]

we have considered LPG and a complete engine change to a diesel.

Do you mean change the engine in the car you have? If so, this is a major task - you will have to upgrade the suspension (diesel engines are heavier), and may need to change the brakes, gearbox, electrics, and other stuff too. Really, the best bet is to buy a purpose made diesel. Converting to LPG is much more realistic.

Diesel engines are generally more efficient than petrol engines because of the way they work, so you will get more mpg and less pollutants. You also have the potential to use veg-oil (basically cooking oil - engine modifications may be needed) or pure biodiesel (modified cooking oil, equivalent to pump-grade diesel). Either of these options will reduce your overall carbon emissions, though I can't comment about other pollutants.

LPG is used in an engine designed for petrol, and while a modern conversion is very good, it is inevitably a bit of a compromise, and will be a little less efficient (this is doubly ironic, because an engine designed around LPG could be much more efficient), But LPG is a much less toxic stuff than petrol, and, in the UK, much cheaper (it is gradually rising in price as demand increases and the tax levy is adjusted ever upwards). It is still a fossil fuel, and as such cannot be considered sustainable, but on my old car the emissions are a fraction of what they are when I run it on petrol (this difference will be less on a new car with multi-way catalysts and sophisticated engine management.

I can only comment about UK conversions (are you UK based?), but before you do anything ask your insurance company what they need in the way of certification - it's by no means illegal or immoral to do a conversion yourself, but the LPGAssociation has pretty well knobbled every insurance company to persuade them that only conversions certified by their members are insurable. So if you do it yourself, expect to pay handsomely to get it certified. If you buy an existing conversion, make sure it has some paperwork with it.

You used to be able to get a grant to convert a car to LPG, but there were several conditions attached, and it often turned out that a grant supported conversion worked out at the same price to the customer as a non-grant supported one. Some people have been rude enough to suggest this was no coincidence. But a year or two ago the EU stopped the UK government giving out such grants anyway. But it may still be worth contacting the Energy Saving Trust to see if any other support is now on offer. LPG converted cars may also be exempt from things like congestion charges and parking permit fees.

It's getting a bit out of date now, but I put up a webpage of links and stuff (including my account of how I did my own conversion) a few years ago.