MPG, how low?

P

Pope

Member
Hi guys

Slight concern.

Last couple of nights when I have taken the Z out for random stuff, shopping, cinema etc my MPG had dropped off a cliff.

I do live in central London, however my drives havnt been stuck in traffic, just general mooching around.

Anyway i reset my MPG and its coming up at around 10 or 11 which is shocking, I usually sit at just under 20 when im booting it around town, however at present I have been taking it quite slow and calm.

Seriously worried as to why its so low.

I need to check my tyre pressures but they all look fine.

Anyone had any problems?
 
Is it genuinely falling that low or could it be a software glitch? Seems a little extreme to me Pope. Worst Ive had in London streets is around 18mpg. I'd fill up and see how many miles you get to the tankful then work it out manually first before worrying too much.
 
spareone3 said:
Is the handbrake off? :wink:
Click to expand...


intresting point you raise, as very recently my handbrake was found to be in the service position after some recent work was done, which was very odd.

And to be honest at the moment it feels a little bit worse when booting it away from some lights etc.

I might have to check this again, but the handbrake is off an no light is on.

It mighy be a faulty sensor, as im still just over half a tank and not loosing fuel, so I dont think it could be a fuel leak.

The one thing that does concern me is that, the car hasnt had a proper thrashing in a few months. Now I no from old that if you dont thrash the hell out of these cars once in while to clear the valves and blow all the crap out of the exhaust they do get clogged up and do have an imact on performance and im a little worried that this might of happened to the Z as it has been a shopping car for the last few months.
 
Allattar said:
The other one could be cracks in the exhuast manifold. Had that one occur to me.
Click to expand...


no nnoticeable increase in volume from engine or the rear if im honest.
 
Well what do you expect if you reset it during urban driving? The Z4M is only rated to 15.5mpg urban 23mpg combined. BMW figures so you generally get less.

If you want a decent measure you need to do some combined like on the motorway and town driving. London is plagued with traffic lights and stopping and starting at them kills the Z4Ms mpg. Depends how happy you are with the throttle too, whether you are smooth or aggressive. If you are booting it from the lights what do you expect? Tbh I would expect those kind of results...

I do mostly motorway and town driving but there is no stopping and starting because of where I live and I average 26.9 over the last 3000 miles but that is calculated over 3000 miles 2.5k of which are motorway miles...

You need to get it out of the city or get yourself a Prius... :rofl:
 
The cold weather has dropped MPG a bit but the lowest you should be expecting with that type of driving is 15-16mpg, even then that's on the low side.
 
tomscott said:
Well what do you expect if you reset it during urban driving? The Z4M is only rated to 15.5mpg urban 23mpg combined. BMW figures so you generally get less.
Click to expand...

I've found the 3.0Si to be slightly worse than the BMW figures but the Z4M much better than the BMW figure, according to the OBC in both cars. I put this down to either one or both being inacurate (unlikely, I would expect them to work the same in both cars) or due to the way cars are tested.As the Z4 M revs higher and has torque higher up the rev range, would they actually rev it higher and therefore cause higher fuel consumption than actually an everyday bod might have when they test them? So if both cars driven the same way, they're not as far apart on the fuel economy front as maybe the test figures suggest
 
Darren M said:
tomscott said:
Well what do you expect if you reset it during urban driving? The Z4M is only rated to 15.5mpg urban 23mpg combined. BMW figures so you generally get less.
Click to expand...

I've found the 3.0Si to be slightly worse than the BMW figures but the Z4M much better than the BMW figure, according to the OBC in both cars. I put this down to either one or both being inacurate (unlikely, I would expect them to work the same in both cars) or due to the way cars are tested.As the Z4 M revs higher and has torque higher up the rev range, would they actually rev it higher and therefore cause higher fuel consumption than actually an everyday bod might have when they test them? So if both cars driven the same way, they're not as far apart on the fuel economy front as maybe the test figures suggest
Click to expand...


I have to agree because I have averaged well over the BMW figures. I read somewhere that they based the mpg on the M3, which is larger and heavier than the Z. They are rated the same. But would you describe London as average urban driving? Because I wouldn't, I would call it extreme urban and any car that does well there is very good. Its not a place I would want to take my M.
 
I'm not sure how you can get 15.5 mpg in a Z4M. I do mostly town stuff with the odd blow out and average 22mpg
 
jamiez said:
Where in central london are you? Fancy a cruise some time!?
Click to expand...

Hey mate, Im Clapham way, black z4m roadster with black CSL wheels and black grills.

flimper said:
I'm not sure how you can get 15.5 mpg in a Z4M. I do mostly town stuff with the odd blow out and average 22mpg
Click to expand...


This is my point, I have had those type of figures for ages, I am heavy footed and do average approx 20mpg, but for it so suddely drop to 10ish was a massive shock.

Im gonna run some diagnostics tomorrow, check Lambda sensors etc and see where we go.
 
Seems a little low even if you reset in town, mine is usually about 15-16 and i do 100% town driving.
 
I had 8mpg but that was on an Andy Walsh day. If you're getting that on the road then something must be wrong I would have thought.
 
I'm just a little south of you guys. I easily get around 18 mpg in central London, and I've the heaviest of right feet. The lowest I've ever seen was 9 mpg on a track day, so I'd say there's something amiss :(
 
I can get 10-11mpg consistently in mine but I'm not sure I'd manage it in Central London :oops:

If I was you, take an hour to head out towards Wandsworth, then find the South Circular past Richmond & Twickenham & it opens up nicely onto the M3.. Take the M25 before the M3 cameras & it's a great windy sliproad, flip around & back off at the next M25 junction & again it's a great approach onto the M3 if it's quiet, by this time sit at 60 in 6th & reset the mpg & i reckon you should be at 25-30, anything miles off this & you have a problem.

Nice little Sundays hour blast too 8)

Other things to consider if it's not being used much would be maybe crap winter fuel or maybe even a throttle reset
 
You must log in or register to reply here.
Back
Top Bottom