Deteriorating MPG - What to do?

[GerH]

Lads,

I have noticed my petrol costs going up and my MPG going down. My question - what can be done to improve the MPG mechanically? Just the usual filters/fluids etc or are there other things that improve the efficiency when changed?

No smart arse MPG posts!!!!

Cheers

[Gar]

Service it new plugs alone usually give 2 mpg ,higher tyre pressure helps too

Remember its winter mpg goes down my own is the same im lucky if I see 100 miles to 30 euro at the moment

[ciars]

Hows the battery and coolant system looking (thermostat)? What does the car indicate (from the hidden OBC menu) after idle and warm versus crawling in traffic (again warmed up) versus driving at 80-100km/h when warmed up?

[GerH]

Hows the battery and coolant system looking (thermostat)? What does the car indicate (from the hidden OBC menu) after idle and warm versus crawling in traffic (again warmed up) versus driving at 80-100km/h when warmed up?

If I reset the MPG on the motorway it will show up to 45/50MPG then as I'm off the motorway it's going down and in stop start traffic it's very poor

[ciars]

Hows the battery and coolant system looking (thermostat)? What does the car indicate (from the hidden OBC menu) after idle and warm versus crawling in traffic (again warmed up) versus driving at 80-100km/h when warmed up?

If I reset the MPG on the motorway it will show up to 45/50MPG then as I'm off the motorway it's going down and in stop start traffic it's very poor

Forget the OBC MPG - access the hidden menu in the OBC and post up the temps for the various scenarios I posted up. Here's the DIY on accessing that menu: http://www.bmwhaus.ie/forum/showthread.php?tid=46

At least then we can rule in or out, the cooling system.

[RobM]

What mileage is on her Ger?

[GerH]

Well less than a year ago I changed the expansion tank. It just hit 160k on the clock Rob.
I'll try the hidden OBC features tomorrow

[ciars]

Any difference in exhaust output worth mentioning? Rough idle? Rough run? Lets know the temps tomorrow for a start Ger!

[Gar]

What kinda figures you getting ger the other halfs is reading 25/26 mpg at the moment all city, best thing to do would be run it too reserves then throw in petrol record how many litres you put in and reset the trip counter then when it hits reserves work it out from there

[John_D]

Any of your calipers sticking by any chance? Check for hot brakes after a journey.
I thought my car was getting bad on juice for a week or two until the symptoms got worse and I discovered a seized rear caliper.