guys thanks for the replies...12 mpg city driving seems a bit oddd....i have NOT changed my spark plugs since now (driven 51k miles) but the car runs smoothly...other than that i have new filters....what is the effect of spark plugs on the mpg..and is 51k miles a lot for a set of spark plugs that came with the car when i bought it brand new? thanks

i think plugs are expected to be changed at 100K by BMW, but that can cut short with aggressive driving (heat wear), bad fuel, and being unlucky. if the plugs dont burn all the fuel and expel some by the Oxygen sensors then it will recalculate the air fuel mixture causing the engine to not run at peak performance and such. (MAF is incorporated too)

try a fuel injector cleaner, nothing abrasive. i think BMW recommends a few.

2006 BMW X5 3.0L CPO giving only 17 MPG
 

Hi,

I bought an X5 3.0 CPO from the dealer last week and ran couple of tanks of fuel till now.The computer is showing only 17 MPG till now.I drive 90% of the highway miles.I don't know why it is consuming so much fuel.I see the forums wherein people are getting around 25 MPG.

When I took the delivery of the car last week,computer was showing 14 MPG.
Is there something I can talk to the dealer (since it is purchased last week) to get it corrected.Or I can directly take it Service at the dealer without talking to him and ask them to run diagnostics and find the issue.
I drive around 60 miles daily.

Please help me out on this issue.

I need to know your secret.... :(

It's a smaller engine pulling the same amount of weight. Unless you drive it like an angel, I'm not surprised it gets less MPG.

All these comparisons of consumption are rather subjective as they all take into account driving style. If you are concerned about a possible fault causing your consumtion to increase then you could attempt to establish a bench mark figure driving at a steady speed. What you need to do is find a long flat section of road and then set the cruise control at 60mph. When speed has been stabilised re-set your consumption meter and run like that for as long as your straight and flat section of road lasts. Just before you turn off the cruise control note your consumption. This figure should then represent the best consumption you can achieve on the open road. This is the figure you should then seek to compare with others as it eliminates the major driver variable. Altitude, Octane rating and wind speed will also effect the result so these need to be noted and taken into account.

If you fuel consumption in this test is normal (i.e. simplar to what others report) then most likely your 12mpg consumption is down to enjoying the performance or your X too much! Of course this test is not perfect as there may still be issues with the tuning of your X that cause it to over fuel under acceleration, but then run fine when at steady speed, but it may be a start.

Since I have a diesel my steady speed consumption will not help you but perhaps others will do the test and post their steady speed consumption for comparison. For interest sake my '06 3.0d gets 35mpg at a steady 60mph at 4000ft altitude. Sea level would improve this figure somewhat.

:iagree:

To the OP: do what JCL suggests: