thats not a good idea then ,what about those 1500cc renault diesels,between 56 bhp and 90 bhp .they have been out for a few years.they are useing them in nissan n v 200 vans [transit size ] the fuel consumption is between 47 to 58 mpg . so a similar engine out of a old renault kangoo may do the job . i am on my third ldv ,i had a 1800cc b type engine then a 2,000cc one ,now a 1900