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Salim

LOW MPG ONLY ON MOTORWAY!?

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I've just bought an E92 330d auto coupe. Around town it does what its supposed to but on the journey back London to Birmingham I got 35mpg!! As it was new years day there was no traffic and I did not go above 80mph, pretty much cruising at the same speed the whole way.

The thing is the last two E92's I've owned (320d and 335d) both also did mid to high 30's on the motorway. The 335d was well maintained and still under BMW warranty. Same with the current car. So what the hell is causing this, is it just my bad luck or is everyone getting shafted like this? 

 

There are no error codes, cannot hear a vacuum leak, both stats have been replaced with OEM BMW and car is getting up to temp. MPG is bang on around town - it only seems to drop significantly at motorway speeds. PLEASE HELP!!?

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is this a reading from the trip?or actual filling up and doing a brim to brim test,trip computers nearly always lie..

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This is the reading from the display, however I know that is fairly accurate based on the amount of fuel that was used up! 

Both in this and the 335, as soon as I hit a flat part on the motorway the instantaneous mpg hits around 40 and at the sign of even thr slightest incline its doing less than 30!!

On the other hand, driving around B'ham in stop-start traffic all day gives me 30mpg (actual) which im more than happy with

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i wonder of its something to do with the egr valve,it really only gets used when driving slow,im only guessing,but it has sprung up in my head,although your car is driving good as you have said..only other thing io can think of is a binding caliper,this would cause a drop in mpg,but again you say its driving ok around town.mmmmmm

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Thank you for your response Rasa. Both ideas crossed my mind. 

There's a receipt in the file for a new EGR controller and with the 335d they also replaced the EGR valve under warranty. So I'd say that might be ruled out. 

 

Binding brakes- hmmmm definitely possible (seeing as that two calipers have already been replaced in the history). However, if my calipers were sticking that bad, would the brakes not have been shot by now? Also, how can I be 100% determine whether they are sticking? 

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Checked the basics? Getting up to temp ok?

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What is the DPF status?

Is it trying to do a regen and failing? As regens use more fuel. And usually happen on the motorway.

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Have you got Carly?

That has DPF monitoring.

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Or an Awron gauge?

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ok googled them. I have the ELM bluetooth adapter so will see if I can get it to work with the two apps u mentioned above

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I know you can start a DPF regen with INPA, but not sure if you can check regen status or soot / ash quantity?

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