I was considering buying a '98 A4 2.8Q. Recently, I read the Consumer Reports review of this car. It states that the car requires premium fuel. Is this true? The 2.8 30v V6 only makes ~200 horsepower, which isn't really huge for the displacement... Can anyone confirm or deny this? Thanks much.

 

Well, she does ask for 91 or higher octane rating. I have a friend with a 01 1.8T who tried to go with regular fuel and his check engine light came on. I am in Iowa and we have Ethanol blended fuel that boosts octane rating and cuts price. When gas prices are spiking high, I drop in 89 rated ethanol and have had no problems.

 

the fuel rating has nothing to do with displacement. do you know the compression ratio of your engine? most likely you would be fine with 87 or MAYBE 85. the worst that will happen is your ecu will detect excessive knock and retard the ignition and dump more fuel in, which you would notice. if this happens you just need to bump up the octane, and reset the ecu. but your engines not gonna explode or nothing.

 

ph and turbo engines are another story

 

The HIGHER a specific octane rating the more a particular grade of fuel resists combustion. Higher compression engines require higher octane because compression causes HEAT, which, when high enough, causes combustion. Modern engines reduce performance by retarding the ingnition. Which helps, up to a point. There is still the matter of high compression.

I ocassionally go with a lower octane fuel, when funds are tight. I try to keep a can or two of octane-booster in the trunk, for these ocassions, but even that isn't always available. A tank, or two, of lower octane fuel shudn't do irreperable harm to your engine/fuel syste.\m, but I wudn't subject my baby to a steady diet of teh stuff. Besides, I get anywhere from 20-30 MORE miles out of a tank of gas when I put premium in than with the cheap stuff...