Your local gas station probably offers you 3 levels of gasoline, like gold, silver and bronze. These typically have different levels of octane in them and you will generally get a little better mileage for the more expensive type.
In addition to different octane levels there are many different additives that can be in a companies brand of gasoline. This differentiation can have a huge impact on your vehicle and even the environment.
One type of additive is a detergent. Detergents clean your engine. Without some level of detergents engine deposits form and this causes reduced fuel efficiency, acceleration and power as well as increasing emissions and rough idling.
In 1994 four auto manufacturers (BMW, General Motors, Honda, and Toyota) recognized the gasoline marketers were not putting enough detergents in their gasoline. They also recognized the U.S. EPA was not mandating a high enough minimum standard of detergents. In fact, after the EPA set a minimum standard gasoline producers reduced the amount of detergents in their gas because the standard was so low.
As a result vehicle owners were suffering reduced engine power, reduced fuel efficiency,
increased driving upsets (rough idle, stalling and surge), decreased acceleration and increased emissions.
These four automakers decided to do something about this problem because they wanted vehicle owners to have a more pleasurable experience with the vehicles they manufactured. They created their own class of gasoline called 'Top Tier Detergent Gasoline', containing a higher level of detergents, meant to keep vehicle owners happier with better engine performance and wear.
In 1994 a few gasoline distributors adopted this new industry standard and since then it has expanded to the following retailers: QuikTrip, Chevron, Conoco, Phillips, 76, Shell, Entec Stations, MFA Oil Company, Kwik Trip/Kwik Star, The Somerset Refinery, Chevron-Canada, Aloha Petroleum, Tri-Par Oil Company, Shell-Canada, Texaco, Petro-Canada and Sunoco-Canada.
I personally discovered this gas by trying the 'silver' gas out at Shell. I thought it would just increase performance for this one tank of gas due to the higher octane. Surprisingly, later fillups with the cheaper bronze gasoline still saw a 5% increase in mileage, not bad for an aging 5 year old car.
This gasoline is good for new cars as it keeps the engine running optimally and especially good for older cars with engine deposits. (ArticlesBase SC #201938)