Hi,
In answer to your questions:
1. When I purchased the car from the dealership they said anything wrong relating to the conversion would not be covered by the warranty. Everything else would be.
2. I used a local LPGA ceritfied company to carry out the conversion. This is an absolute must. In addition, you need to speak to people who have had the conversion carried out by the company you are intending to use. Several different systems exist. The best are Prins, Romano and BRC. I have a Romano system fitted. Make sure you do your research.
3. I have worked out my MPG to be 35MPG. Which means as the price is half what unleaded is, equates to around 70mpg in monetary terns.
4. No neither of these are covered. However to be realistic, I have not known of a car which has had cat problems since being converted. The fuel is cleaner running. As for valve seats. Only certain engines are effected by this. Mainly engines with soft valve seats. The liquid fuel lubricates these. Gas doesn't and it burns slightly hotter also. I was informed by several installers that BMW engines do not have this problem. If you are worried, a product called flashlube can be injected at the same time as the gas which provides this lubrication.
In additon, Mini will not service the LPG parts but I was informed by the dealership (sales and service) that my TLC would still be covered.
I would think twice before having the conversion done and think if after the cost of the conversion (roughly £1500) if you will recoup this in fuel savings. I know I will as I travel 40000 miles a year.
I have now done over 10000 miles on LPG since conversion. I cannot, however say this was trouble free as it took the conversion specialist a number of times to tune it correctly. Saying that, it's running fine now.
Before you convert look into the following:
1. Will you insurance company cover an LPG converted car? - Most do for no additional premium.
2. If you get GAP insurance check they will cover this. One phone call and this was sorted.
3. Recovery - I'm not sure Mini would help if the car had a breakdown caused by this. I found cheap (£35 per annum) cover that would.
4. Warranty - I went to warranty direct and although they wont cover the conversion (you converter will with a 12 - 24 month warranty) they will cover anything that has been caused by the conversion.
5. I no longer have a boot - which I'm not too bothered about.
I'm not trying to be negative about all this, just honest!!! After conversion costs I will save around £3000 over the next couple of years
Hope this lot helps.
Anymore, just ask.