anyone experienced reduced gas mileage after installing Stillen coldair intake in G35 coupe?

With the stock intake, i was getting around 350 miles/tank. After putting on the Stillen CAI, im getting like 300 miles/tank. Anyone knows why? Intake is the only mod i have in my car

Thinking of going back to stock but i dont have stock intake anymore cause the dealer installed my Stillen intake and i forgot to ask for my stock intake back.

An intake should not bring your MPG down. If anything, it might be that you changed your driving habits. Too many factors to give you a conclusion.

Many have stated their MPG has gone up after installing an aftermarket intake.

Im guessing you have a typo on your MPG amounts. 350 MPG

I don't think it is the intake that is causing it. Ur right foot has a lot more to do with it since u enjoy hearing the intake more.

It wasn't a typo. I just had the 60k service done on my 2003 G35 Coupe at the dealership. They added the 44K to my fuel tank and told me that i would experience better gas mileage for the next 400 miles. So i started tracking my mileage. I was getting a consistent 350 mpg/tank until i installed the Stillen CAI.

I didn't change my driving habits. I tried to drive very moderately and still only could get 300 mpg/tank with the Stillen CAI. I think it's the Stillen.

Oh, so you mean 350 miles per tank, not MPG.

Either way, it can't be the stillen. Something else has changed your MPG; its either your driving, or something in the engine compartment itself.

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my bad i meant 350 miles/tank... didn't notice that

actually, there are a number of members on this forum that average 350-400+ mpt.

eminem, have you changed your driving routes/habits at all? perhaps more street (stop/go) driving?

I was refering to his "350 MPG". I too average over 350 miles per tank ... I think.

I think its theoretically impossible for an intake to worsen anyones MPG if its installed properly. An intake might lean out the AFR mixture; it's going to add more air to the mixture rather than fuel.

It's all behind the driving.

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I have been running the Stillen Hi-Flow Airbox for over a year and have had no mpg issues.

You might try to reset your ECU just to be sure but 50 miles per tank sounds a lot more like your right foot is the cause.

have you check you tire pressure could be something like that

no guys i haven't changed my driving habits... i intentionally tried to drive very moderately like i did before i installed the stillen intake (mostly on freeway at around 75 mph) just to find out how many miles i could get after i installed the stillen intake... and i have been getting around 300 miles/tank

i guess i can check the tire pressure

You may not think your driving habit haven't changed, but they did the
minute you installed the Stillen CAI. Your subconscious is listening to the
sweet sound the intake is making and your right foot is reacting if you
know it or not! This works the same way when you install an exhaust
system. Customers complain that their gas mileage has gone down hill but
it's their right foot causing the problem.....most don't believe it but this is
the truth! We react to the sweet sounds are cars make, and I'm guilty too!
You may try disconnecting the battery for an hour and then reconnect but it
really won't make any difference......Happy Driving.
Dr. Gary C.

miles per tank is also a very poor measurement of gas mileage, as a "tank" varies quite a bit depending on when you fill up. MPG is the generally accepted method for measuring gas mileage as it doesn't have the tank variable

ok thanks guys, maybe it's the way i drive. I would rather not go back to stock because i like the way the stillen intake looks and sounds...