Just bought the Mazda CX-7, and I gotta say it is beautiful. The one thing I was not aware of prior to buying it is that it requires Premium gas! If I were to use a lower octane gas would that really hurt my engine, or will it just reduce its power? I've read on some reviews where it says that it can run on regular unleaded but it only reduces power. I would like to know what you all think. Any thoughts will be greatly appreciated.

I would run the premium. Running the lower octane will reduce your power output, but also your efficiency in the motor...i.e., you'll just end up using more of the cheap gas, so the $$$ saved won't be significant.

Assume you drive 20,000 miles/year and get 20 mi/gal (to make the math simple), you would consume 1,000 gallons of gas.

Say 87 is 2.90 and 93 is $3.10 (Typical spread in MI is about $0.20)

It would cost you $2900 to run the regular and $3100 to run premium.

Now take into account the efficiency...If the engine loses 5% in efficiency, you'd burn 1,050 gallons @ a cost of $3,045.

So you'd save ~$55/year (with the above assumptions.)

Great post about the gas.....and yes premium gas is way worth it!! I have an RX 8(rotary engine) and it runs horribly on anything less...loss of power, idles bad etc.

Well with the Rx-8 or Cx-7 they are high compression vehicles and running anything lower than reccomended will have a threat of detonation (destroys vital core engine parts) and would be VERY expensive to fix and not under warranty mind ou because you didn't follow the instructions in the owners manual. Just spend the extra money, it's not worth the risk of blowing up your new engine.