Motorhomes will have either a gasoline or a diesel engine. The type and price of the RV you decide on will usually dictate the type of engine you get. Class B and Class C motorhomes will almost always have gasoline engines, as they are based on the chassis of gasoline-powered vans.

A mid-price Class A motorhome will probably have a gasoline-powered engine, though you may be able to spend more and get a diesel engine. If you are buying a large, heavy motorhome and intend to use it for many long-distance trips, diesel makes sense. Diesels will cost more initially but are usually cheaper to operate and have fewer maintenance problems. Quality-built diesel engines can rack up an impressive number of miles before needing a major overhaul. Diesel fuel is about the same price as regular gasoline, but you will get more miles to the gallon. Another factor is fuel availability. There is usually a gas station on every corner, but most sell gasoline only. The easiest place to find diesel fuel is at large truck stops and at gas stations just off major highways. As large RVs are more suited to major highways, finding fuel should not be a problem. Most of the large bus conversions have gas tanks that hold almost enough fuel to get you hundreds of miles; the chances of running dry are very slim.