There is some postulation that one could get better mileage using Top Tier fuel from companies like:

QuikTrip
Chevron
Conoco
Phillips
76
Shell
Entec Stations
MFA Oil Company
Kwik Trip/Kwik Star
The Somerset Refinery, Inc.

Top Tier gasoline has been recommended by General Motors, Toyota, Honda and BMW. But not because Top Tier might net better mileage. They recommend Top Tier because of concerns about the low levels of detergent additives in gasoline.

Over the past several years, the minimum level of detergent additive required by the EPA has declined by an estimated 50%. As a result, the ability of vehicles to maintain stringent Tier 2 emission standards have been hampered, leading to engine deposits which can have a big impact on in-use emissions and customer satisfaction.

I am one of those who believe you should shop for, and buy, the least expensive fuel you can find. Top Tier fuel can be ten to twenty cents per gallon more expensive.

There is also a problem with the idea of lots of additives: Tide with Bleach requires a larger capful to clean clothes, and gasoline with additives suffers from the same dilution problem. If I lose MPGs to a dirty engine or lose it to diluted gasoline, I still lose it.

But one should use a gasoline based on their personal values. Top Tier if you care more about the environment (and if you plan to keep your car for 5+ years). Tier 2 gas if you care more about costs of daily transportation.

We probably have an equal number of both on this site.

Boy, is that the truth. The very first Nissan salesman we talked to was a total slime bag. He tried hard to play with our heads regarding the Camry hybrid... and tried to make it sound like a bucket of junk that would fall apart at any second... even alluding to numerous class action suits he thought would hit the car... but when we quizzed him about the Altima hybrid he knew NOTHING about the car... nothing at all... he didn't even have a good knowledge of Nissan cars... so how was he supposed to be the world's greatest expert on the Camry hybrid? He actually did a lot to turn us off on the idea of getting the Altima hybrid altogether. The Camry hybrid is a great car, and it was a truly stupid sales technique to try to pretend to be an expert on the competition's car when you aren't even aware of the base components of your company's own vehicle.

Down the line, none of the salemen we talked to on any of the hybrids knew much about the cars. We had to do all our own reading.

I have learned to do a lot of reading, Take multiple test drives. I have little conversation with the salesman. I always work with the Internet saleman or Fleet department. They don't know any less but at least are more prone to be quite and just answer a question they will always answer a question even thought they don't have the right answer.

I think they are so busy trying to get a sale to get the comission so they can support themselves they don't have time to read on the job and they would never think about reading at home. They don't think of their jobs as careers. Even those that have been there a long time don't do home work just gain knowledge over time. You might call ahead and ask who has been at the dealership the longes and MAYBE get someone with a bit of knowledge.