I got this from a RV tech news letter I receive. I thought this was interesting. Most of us know this.
Advantages & Disadvantages
of Diesel–Engine Power
Advantages of Diesel–Engine Power
Durability
The engine is designed to operate continuously under sever conditions at full power. For owners who plan to keep a motorhome for many years and roll up lots of miles, diesel is the obvious choice.
Torque
Diesel–engine horsepower ratings may appear low when compared to gas engines of the same displacement, but torque is the overriding performance factor in heavy vehicles. Torque is defined as twisting force applied to the driveshaft and hence to the wheels, propelling the coach. Higher torque means more energy applied to the wheels. Diesels produce high torque at low engine rpm, providing a strong, steady driving force.
Economy
A gallon of diesel fuel contains more energy than a gallon of gasoline, and the diesel engine makes better use of it via higher compression. Diesels get better fuel mileage than gasoline engines under the same weight and road conditions. Of course, the buyer must pay more for the diesel engine at the outset, which must be amortized by the fuel savings.
Resale Value
A diesel–powered coach usually holds its value better than a gasoline–powered unit, reflecting the diesel's durability and fuel efficiency and its higher purchase price.
Disadvantages of Diesel–Engine Power
Cost
The cost to manufacture a heavy–duty diesel engine is several times that of a gasoline engine because compression in diesel engines is very high (20:1). Another factor that raises the price of diesel coaches is the additional cost of a heavier–duty transmissions, which is necessitated by the higher torque output of the engine. Made by Allison Transmission, the units have four, five, or six speeds, depending on the torque output of the engine.
Noise
Diesel engines produce a higher level of noise than gas engines, although while traveling, the noise is isolated from the driver and passenger in rear–engine motorhomes. This noise may be difficult to tolerate for some, but it's music to ears of others.
Braking
Diesel engines do not offer as much compression braking force (drag) as gas engines do, and speed retarders are fitted either to the engine or transmission. The engine–mounted units are exhaust brakes, essentially turning the engine into a compressor, and the transmission–mounted units retard speed hydraulically.
Maintenance
Diesel fuel produces more combustion byproducts than gasoline, and the crankcase usually contains more than twice the oil capacity of a gasoline engine, raising the cost of maintenance. The price of engine components is higher for diesels than for gas engines, as is repair work; neglecting maintenance can be very expensive.