135i Coupe Bad MPG - Alpina Flash

[Christian_E90]

I just purchased a 2009 135i Coupe automatic and so far I am loving the car, the M sport suspension is to die for and the cars absolutely hauls compared to my FBO 335xi.

However, I have noticed that the gas mileage isn't as I expected it should be.

In my 335xi with gentle driving I get 17.x mpg.... however in the 135i WITH the alpina trans tune and doing a decent amount of highway driving, I am getting 18.0-18.2 mpg, and that is with driving like a granny.... I really don't know what explains this. My friends 335 sedan with MHD and Xhp trans tune gets over 19mpg and he drives it WAY harder compared to my driving style, it just makes no sense.

I'm not sure If the intake valves need to be blasted (car has 79k miles) but by all means I am shocked that it is getting such poor mpg.
Please give me any advice on what I should do, or an explanation to this. Thanks all

[TM9030]

Ditch the Alpina Flash! Go with the stage 2 xHP Flash. Also, if tuned make sure your using the correct map. I was having the same issue and after some research I found that the previous owner was using an MHD map without the supporting mods. Once I flashed the car back to stock the issue went away and my MPGs got better.


Now with City driving I average 19-20, before flashing back to stock I was averaging 14-16.

[elitesales305]

Originally Posted by Christian_E90

I just purchased a 2009 135i Coupe automatic and so far I am loving the car, the M sport suspension is to die for and the cars absolutely hauls compared to my FBO 335xi.

However, I have noticed that the gas mileage isn't as I expected it should be.

In my 335xi with gentle driving I get 17.x mpg.... however in the 135i WITH the alpina trans tune and doing a decent amount of highway driving, I am getting 18.0-18.2 mpg, and that is with driving like a granny.... I really don't know what explains this. My friends 335 sedan with MHD and Xhp trans tune gets over 19mpg and he drives it WAY harder compared to my driving style, it just makes no sense.

I'm not sure If the intake valves need to be blasted (car has 79k miles) but by all means I am shocked that it is getting such poor mpg.
Please give me any advice on what I should do, or an explanation to this. Thanks all

Dirty o2 on rear of cat?? My dct n55 would get 275 easy.. and that was beeing conservative on the later part of the tank.. all highway tho.. factory
N55 mt with stage2 and supportinf mods.. 250 if im lucky..
what do your numbers look like on a full tank?

[Tiron]

Having owned a 6AT 335i and an MT 135i, the 135 just gets worse mpg. I tend to drive manuals harder than autos (since it doesn't upshift for me, I have more fun), but even steady speed cruising the mpg is worse. The aerodynamics on the 1 series are not as good as the 3, and the MT has higher RPM on the freeway as well.

335i would routinely get 19-20mpg around town and probably 27-28mpg highway. Best tank was 32mpg all highway with some lucky wind.

135i seems to be 16-18mpg around town (probably from MT) and more like 24-25mpg highway (probably from worse aero). Around town I average about 200 miles to a tank at 12 gallons.



If you are getting 18mpg all highway or are suspecting a mechanical problem, I'd think an aging O2 or leaky injector maybe.