Gas vs Diesel Engine Buses

When it comes to gas vs diesel engine buses, there are advantages and disadvantages to both types of engines and fuels. When it comes to environmental impact, it’s a draw. Historically, diesel engines struggled with producing higher emissions when compared to gasoline powered engines, but today the difference between gas and diesel emissions is minimal, due to regulations imposed by the Environmental Protection Agency (EPA). Both types of emissions have been about the same since the EPA implemented new emissions requirements for diesel engines in 2010.

When looking at fuel cost per gallon, gasoline has the advantage. “Historically, diesel has been more expensive per gallon as a result of higher taxes and environmental restrictions,” stated Steve Jansen, truck services account executive at a Northbrook, Illinois based fleet leasing and management company. However, when it comes to fuel efficiency, diesel is the winner, according to the U.S. Department of Energy, with diesel engines offering 30 to 35 percent greater fuel economy than comparable gasoline engines.


“By design, diesel engines operate with a combustion process that’s leaner, burning less fuel than a conventional spark ignition (gasoline) engine,” explained Roger Gault, technical director, Truck & Engine Manufacturers Association (EMA), a trade association representing worldwide manufacturers of internal combustion engines used in applications such as trucks and buses; farm and construction equipment; locomotives; marine vessels; and lawn, garden, and utility equipment. Diesel fuel also has higher energy density than gasoline, which means less fuel is required to generate the same power as gas, improving overall fuel economy.

One down side to using diesel is availability of diesel fuel can be limited by location, as some gas stations in certain parts of the country do not have diesel fuel pumps alongside their gasoline pumps, making it difficult to refuel on cross country trips. Diesel engines do have the capability to run on bio-fuels, however, which produces cost effective vehicles that run more efficiently. This could help make diesel powered vehicles more attractive to consumers as bio fuels become more available. Although diesel fuel is a little more expensive at the pump, it is more cost effective than gasoline, as it produces more energy per volume and offers drivers better mileage per gallon than gasoline.

Diesel engines also do not use spark plugs; rather they operate by a compression ignition system rather than a fuel injection system. This difference alone can increase the efficiency of a diesel engine over a gasoline engine. When it comes to hauling a load of equipment or passengers, a diesel engine is the better choice simply due to torque. Typically, gas engines make more horsepower, while diesels produce more torque.

If you are going to run a bus with a full load of passengers, you will put a larger strain on your vehicle’s engine. Diesel engines were built to maintain power with heavier loads during extended periods of time without placing heightened strain on the engine. A gasoline engine can lose power in a fully loaded 32 passenger bus.

If you are in the market for a new addition to your fleet, or just looking for the perfect bus to get you and your crew where you need to be, call Davey Coach today and let us help you find the right size and type of bus for your organization. (800) 873-1856.