Ive had a 6.5 diesel chevy based coach which averaged 13 mpg over about 25k miles and I now have an 8.1 petrol on a workhorse chassis which averages arond 10mpg, you will get more if you drive around 50mph but with 8 litres under the bonnet the coach is raring to go and cruises beautifully at 60 ish. LHD is not problem and on some narrow UK roads it is a positive advantage as it is easier to hug the kerb and keep your offside mirror intact!