Premium fuel really necessary?

My wife has her eye on the Mazda CX-7. It supposedly has to take premium gas. Here are the motor specs:

2.3L 16v turbocharged 4cyl
244hp @5000rpm (6700rpm redline)
258 ft-lbs torque @ 2500rpm
137.9 cu. in. displacement
bore x stroke: 3.44 x 3.70
compression ratio: 9.5:1
electronic direct injection

Does it really need premium fuel (recommended 91 octane)? I think many times manufacturers say this but regular fuel will work just fine. This would be driven almost exclusively in FL, basically at just about sea level. Does the turbocharger (standard on all models) really make it necessary?

In my experience, with the 1g eclipse gsx's and 4g jetta 1.8t (both turbrocharged), it isnt fully necessary to run 91octanes, but you will notice a differance in performance running regular or even plus fuels. Also your engine (again in my experience) pings more than it should, especially of these 4cyl's.

But if its just for casual driving, and not "speed racer" you should be fine, but everyonce in a while through in a tank of that premium.

i had a subaru with a turbocharged H4 and running anything less than 91 would set off my CEL with a code for oxygen sensors... i think this is more a general problem with subarus though, because i also had issues with 91 octane gas that came from a local Wawa.. but no problems with gas from Exxon

the ecu on the vehicle will notice the pinging and retard the timing and possibly decrease the boost accordingly so that you do not harm the engine due to the detonation.

i would never sacrifice boost to save a few bucks at the pumps. takes all the fun out of owning a turbocharged vehicle.

Being almost the king of all that is rationalization...I see the cost difference per tank between reg & prem as about the same as a foo-foo coffee drink that I can make for myself at home for a fraction of the cost... :rolleyes:

Every time she fills the tank, omit one trip to Starbucks... ;)

have u checked the mpg between 91 and regular? i would expect a drop in mpg due to lower hp and the need to gas it more.

Not much different than my WRX really. Anything less than 93oct bogs it down and creates the same effect you get from turbo lag. The engine runs warmer with that airflow, so you need some fuel thats gonna be ready to burn away. Unsure if prolonged use of low octane causes damage, but I would speculate that it does since the car gives immediate feedback when it's used.

Besides, its a turbo.... higher octane is the price you pay for a zippy little SOB. ;)

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Originally Posted by WormGod

Besides, its a turbo.... higher octane is the price you pay for a zippy little SOB. ;)

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Ditto!

Yes, absolutly. Don't waste time with a boosted engine if you can't afford,or don't want to afford ,to feed it...neither of you will be very happy (the engine, not the wife)

Like the CX-7 ........ CX-7 is my next vehicle.

My wife liked the CX-7 (and the dealership, which was totally no pressure and actually an enjoyable experience). But minutes later thought she had just looked at an Acura. :-)

If she doesn't know the difference,why you at a mazda shop??? Sounds like a quick trip to the Kia boys, to look at their "top of the line" Accent ,is in order.