Dear Terry,
I read your response to the question about whether or not using bargain gas will hurt your car. It is a very interesting article.

You stated the following:

"Some manufacturers say that today's high-tech engines require higher-standard gasoline than the EPA benchmark. Audi, BMW, General Motors, Honda, Toyota and Volkswagen have worked with major gasoline companies to set a standard for what is known as Top Tier Detergent Gasoline.

"Gas companies that meet these standards include QuikTrip, Chevron, ConocoPhillips, Shell, MFA Oil Company, Kwik Trip/Kwik Star, The Somerset Refinery Inc., Aloha Petroleum, Tri-Par Oil Co., Texaco, Petro-Canada and Sunoco-Canada."

Is this a complete list of gas companies or are there others, such as Exxon Mobil, Gulf, etc.?
-- Sandy

Dear Sandy,
According to the official Web site, toptiergas.com, other major retailers like Exxon Mobil and Gulf do not meet the top-tier standards. As I discussed in my answer, debate continues about whether using those non-top-tier gasolines will damage your engine.

Here are this week's reader questions:

• 'Feebates' target gas-guzzling drivers • How can I get my name off a loan? • Can a car depreciate $10,000 in a month? • Do all major retailers sell top-quality gas?

If you have a question for Terry, e-mail him at Driving for Dollars. Save money on your car -- sign up for Bankrate's new weekend Car & Money newsletter.