Z3 2.8ltr MPG

[Drop_Gear]

Hey guys, Newbie here.

I got myself a Z3 2.8Ltr (1997) a few months back . And I am wondering if I should be getting better MPG than I am . I've just used up a tank over 185miles of mixed (fast and slow) city road driving, but even with motorway miles of 75-85mph I got 230miles to a tank. I have a feeling that something is wrong, as I read a Z3M driver got 220-240miles of fast driving to a full tank...

Any ideas/ known problems?

Cheers

[XVar]

Sounds about normal to me, I get 30mpg on a motorway run and about 18mpg with "spirited" driving. Used to get 240 miles out of a tank when it was my daily driver, mixed motorway and urban. A Z3M getting 220 miles off a tank being driven fast just isn't true, a Z3M gets closer to 10mpg on a track!

[Z3andZ4]

It's a good question.

As you can see I have a few BMW's..........and have a had a few more in the past M3's particularly.

One thing I have found is the mpg readings in the car can be misleading - so excuse me for potentially telling granma etc etc - but when I feel particularly like checking I brim the tank and calculate a tank full brim to brim. On this basis and without dawdling of racing I reckon I get pretty close to 30mpg in my Z4MC. I reckon the Z3 3 litre is nearer 35 and the Z4 3 litre a little less. HOWEVER I do not drive 'full on' much anymore, hence my clean licence.

I would have thought that you should expect 30mpg from the 2.8 litre although I have no recent experience of one as I last had one when it was a P registration plate!!

I do enjoy having a blast from time to time, especaially overtaking - but these days the speed limits are best adhered to or the points quickly accumulate.....

The killer for me was driving my Z4MC in London - now that truly dropped the mpg to less than 20 I think. I found the best speed/economy was definitely between 60-70mph and all the other stuff just sucked juice for no joy.

Sorry, that probably doesn't help much.

[Mike Fishwick]

A lot depends on where and how the car is driven - for example, many people complain about poor fuel consumption, yet commute slowly for short distances, where the engine never warms up. My Z3 has always given good fuel consumption, one of the key reasons being the life it leads. On quiet rural French or German roads I usually get about 36 mpg, and have seen 38 to 40 mpg, though that is unusual. UK motorways give 36/37 mpg, French Autoroutes 32-34 mpg.

These figures are calculated on a 'Full to full' basis - the trip computer is about 10% optimistic, probably due to calculating in a 5 litres to the gallon basis.

I tend to avoid heavy accelleration, and always use 98 octane fuel, which gives about an extra 10%. Although difficult to find in the UK, it is readily available all over Europe, for only about 3% more than 95 octane.

In the UK fuel quality can be terrible - I have always found Esso to be the best, in both 97 and 95 octane forms. BP Ultimate and Shell V-Power were disappointing in both the UK and France, being no different than 95 octane, probably due to an overdose of ethanol. In France V-Power was about 4 mpg worse on a long autoroute run than my usual supermarket 98 octane.

One of the most common reasons for poor fuel consumption on older BMWs is that the brake pads are rusted to their carriers, causing brake binding. All the usual things also apply, such as old spark plugs, dirty air filters, old oil in the engine, gearbox, and final drive - and of course K&N conical air filters without a heat shield, drawing hot air from behind the radiator.

[Drop_Gear]

Thanks for the reply guys. The car has just notified me that its in need of a service II, so I will get that done asap and see how that affects my MPG. I have just replaced the roof as it was leaking, so the service will have to wait 2 weeks (next pay check). The car has only 51k Miles on the clock, so I would have thought I would have got close to dealer figures!, but if my calc are correct i'm doing 18mpg city... at least I know there isn't anything wrong. Only joined up yesterday, so will put up some pics later on this week and start a thread as I have many plans.

[Geoff H]

I think you will find your MPG about is about right for a early 2.8, the later twin VANOS 2.8’s do give better fuel consumption. I get about 200 miles for half a tank, on short journeys using Supermarket fuel. I’ve not checked the actual consumption for years, but I always fill to the brim when it gets to half a tank and trip the clock (force of habit) and it’s always around the 200 mile mark

[Mike Fishwick]

Forgot to add, but I always reset the Service Indicator lights at about 'two and a half' lights, as I find fuel consumption rises after that.

Peopletend not to believe this, but I have found that it really works - and the difference between the red light and resetting is very noticable in tems of engine performance and fuel consumption.

[BladeRunner919]

Forgot to add, but I always reset the Service Indicator lights at about 'two and a half' lights, as I find fuel consumption rises after that.

Peopletend not to believe this, but I have found that it really works - and the difference between the red light and resetting is very noticable in tems of engine performance and fuel consumption.

I've read this in a few places and I did see an increase in MPG after resetting my service lights. I should qualify that by saying that I've only had the car since Feb, so haven't done this more than once to see if there really is a trend.

[OldskoolRS]

I think you will find your MPG about is about right for a early 2.8, the later twin VANOS 2.8’s do give better fuel consumption. I get about 200 miles for half a tank, on short journeys using Supermarket fuel. I’ve not checked the actual consumption for years, but I always fill to the brim when it gets to half a tank and trip the clock (force of habit) and it’s always around the 200 mile mark

You have to consider that your fuel gauge might not be very even in it's display. FWIW I get around 26mpg from my 3.0 and it's around 250 miles or so down to near empty when I refuel. I have got 30mpg on a run that was mostly motorway at 80-85mph (obviously abroad ) but I didn't buy it for mpg.

[orange]

My trip computer says I'm averaging 31.9 in my 2.8. Most of my driving is mainly commutes to work along country roads - when the weather is nice!
I think I got 34 when we had a trip to south wales along motorways. But motorways are not where I really want to drive my Zed
I don't think I'd have bought the car if fuel economy was top of my shopping list....fun was!

[Geoff H]

I think you will find your MPG about is about right for a early 2.8, the later twin VANOS 2.8’s do give better fuel consumption. I get about 200 miles for half a tank, on short journeys using Supermarket fuel. I’ve not checked the actual consumption for years, but I always fill to the brim when it gets to half a tank and trip the clock (force of habit) and it’s always around the 200 mile mark

You have to consider that your fuel gauge might not be very even in it's display. FWIW I get around 26mpg from my 3.0 and it's around 250 miles or so down to near empty when I refuel. I have got 30mpg on a run that was mostly motorway at 80-85mph (obviously abroad ) but I didn't buy it for mpg.

Your 3.0 will be a twin VANOS so should give a better fuel consumption. I don't use the OBC to see the fuel consumption, also that needs to be reset regularly to see what you have done on a set week / journey. I just fill up to the brim each time the fuel gauge gets to about half a tank, and trip the clock back to zero, and its always around about 200 miles for half a tank. If I had brought it for fuel consumption I wouldn't have owned it as long as I have.

[OldskoolRS]

I do glance at the OBC, but my mpg figures are calculated from brim to brim figures. I started doing it as soon as I got the car, just as a kind of history. It showed that replacing a faulty camshaft sensor did increase mpg a little as did changing to Superunleaded, but it's more of a side interest: I'm more interested in taking it out for a red line blast as often as the weather and time allows. I did drive round the M25 on Friday though, but this was because I was having a rare visit to my office and I'd promised a colleague a spin in it at lunchtime...he went back to work with a big grin on his face. Shame I then got stuck in traffic coming home, but at least it was sunny and I had the rood down.

[Geoff H]

Yes a lot depends on driving style too, I've just been out to the garage and looked at mine, its not been reset for a few years now. But I do enjoy driving it as the consumption shows

[Geoff H]

Was interesting looking at this Technical Data sheet Robert T has just posted http://www.zroadster.net/forum/viewtopi ... 18&t=35286 ,after posting a reply to this MPG thread earlier today. It states 21.9 mpg for Urban for my 2.8 which is not far off the 19 to 20 mpg I usually get for short trip town driving, and 30.1 mpg for combined use which is in line with what some other posters have put. The only other factor which would make a difference is the driving style of the owner

[Robert T]

I was looking up something on tyres in the back of the manual earlier and thought it would be worthwhile posting up some of the info in there. It's not complete yet (still need 2.0, 2.2 and 3.0 data), but will hopefully make a useful resource for the future.

Cheers R.

[Drop_Gear]

Hey guys I believe I read somewhere that the fuel level sender? can send an incorrect signal to fuel gauge? and its a common problem? is this true...

[Zed Carer]

Hey guys I believe I read somewhere that the fuel level sender? can send an incorrect signal to fuel gauge? and its a common problem? is this true...

Mine sends an inconsistent signal; e.g. fill up and needle goes to full, drive 50 to 60 miles needle still only just off full, drive another 20 to 30 miles and it drops to 3/4 full - on average it's 70 to 80 miles to get down to 3/4, around 150 miles to get down to 1/2 and 225 miles to get down to 1/4 but it does it in jumps rather than smoothly.

Average for me (99 2.8 M52TU) is around 29, can get 33 / 34 on a long steady run with the OBC saying 38mpg (if only!!!).

[msassoon]

That is about what I get. The fuel economy was bad for a while, but I changed the spark plugs and it shot back up to normal.

[c_w]

As has been mentioned the later dual vanos 2.8 is much better on fuel and also power IMO, mine was really quick and pretty frugal too, high 20s were easily achieved as mixed driving, with near 40mpg on a steady cruise.

[OldskoolRS]

I'm impressed at the mpg some are quoting for the 2.8. I was under the impression that my 3.0 should be more economical than the 2.8, but even on a run 30mpg (from the OBC which does seem to be fairly accurate compared to my brim to brim readings) seems about the most I get. At 64,000 miles I wonder if it's worth replacing the spark plugs on mine as I can't see any mention of it being done in the history? No error codes now (due to a camshaft sensor replacement) and a fresh air filter has already been fitted.

[spurs fan in a coupe]

My 2.8 does about 200 miles to about 35 litres.

No idea what that makes my MPG but some people say I have a heavy right foot.

As others have said, didn't buy the Zed for its economy but have been surprised. 65,000 miles so far, lots of petrol, lots of tyres, quite a few services but nothing unexpected has gone wrong (touch wood). MOT today advisory on rear brake pads (fronts were recently changed to Red Stuff and Pagid (http://zroadster.org/forum/viewtopic.php?f=52&t=370)) and a slightly worn brake hose. Clutch release bearing was noisey when I bought the car, repaired the rear subframe/boot floor, de-cat after coroded mid section.

[gookah]

Don't know why people harp on about the price of petrol,
I put £30 in every week, and that's never gone up......
It's the miles that are obviously longer nowadays, 'cos I do less of them