do you think it's working properly.

[jeff666]

ok i have owned my e46 330 sport coupe for eighteen months now,how accurate are the obc? wnen i bought the car it was showing 29 mpg now it seems to be stuck on 27.4 mpg , its been on this for ages and does'nt go up or down regardless of how its driven ie long journey or round town. its a manual with 78,000 mls on it. what mpg are you guys getting out of same car?

[Flat6]

Same happened on my 130i. More miles I put on it the less the MPG changed. Unlike some other cars the OBC doesn't reset after a certain amount of driving, so the MPG is calculated over a longer and longer period. No matter how I drove the 130 it wouldn't move from 32.1mpg - until I reset it. Keep the button pressed for a few seconds and it should reset...

[jeff666]

Flat6 said:

Same happened on my 130i. More miles I put on it the less the MPG changed. Unlike some other cars the OBC doesn't reset after a certain amount of driving, so the MPG is calculated over a longer and longer period. No matter how I drove the 130 it wouldn't move from 32.1mpg - until I reset
it. Keep the button pressed for a few seconds and it should reset...

cheers for that will give it a try.

[8Tech]

That display is showing you your average mpg since you reset it last, NOT your current mpg. Reset it on a cold engine and then go for a brisk or around town drive and it will probably show around 15 mpg.

Get the engine fully warm, put your cruise control on at 60 mph on the motorway and then reset and you could see 40+ mpg.

I think this is the only way to get an "instant" mpg reading from the later cars.

[DSM2]

Flat6 said:

Same happened on my 130i. More miles I put on it the less the MPG changed. Unlike some other cars the OBC doesn't reset after a certain amount of driving, so the MPG is calculated over a longer and longer period. No matter how I drove the 130 it wouldn't move from 32.1mpg - until I reset it. Keep the button pressed for a few seconds and it should reset...

Spot on. No auto reset so the longer it is run for the more stable it will become. After 2/3K it will rarely move much.

Reset it, then you'll see.