If you have a relatively new petrol car or light commercial vehicle ,or even a black cab that needs a new engine , then the answer is to convert it to LPG. 

If you have diesel cars or vans, or an older petrol car or light commercial vehicle that is on its last legs then the answer is not to convert to LPG but to buy a new LPG vehicle. We do not convert diesel cars and we don't recommend that you do this.