Fuel consumption, what can be achieved?

[tominator]

Hey guys, I bought a 2008 Z4 coupe 3.0si sport, 38,500 miles last November, drove it back home pretty steady around 220miles and averaged 36.5 mpg....not bad I thought for a 3.0L engine.
I haven't driven it that much over the winter months just taking it out on sunny days, and when I do have a drive I like a mixture of hard driving and nice and steady averaging round 27-28mpg, again not too bad, considering my 1.8t golf gti only averaged 25mpg.

I've read on here somewhere a topic on fuel consumption (can't find it now) where folks had seen average figures of early 40's mpg, I was intrigued so thought i'd give it a go and see what could be achieved.
My Z4 hasn't got CC so purchased the stalk and wiring loom and set of down to Northampton from Wolverhampton yesterday (75 mile approx) to have it fitted by Damesb who had previously fitted his own to his Z4 coupe. The journey down was not too busy, I tried to stick to around 60mph, and managed to achieve 42.8mpg

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I was really pleased with the figures but thought that maybe with cruise control I could do better.

Big thanks to Damian (Damesb) with help in fitting CC

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Drove down to Oxford to visit my son and watch Joshua v Klitschko fight then set off for home 92 miles. All motorway m40, m42, m6, m54, then half a mile to home, roads were pretty quiet so no lorries, no one to slow me down, only overtook a couple of cars, and one lorry if I remember correctly.
Activated the CC as I drove down the slip road of the M40 and set it too approx 57mph, this was set for the entire journey just increasing speed to overtake a couple of times.

Around 50 miles into the journey I hit 47mpg, and there it stayed for the remainder dropping down to 46.6 a couple of times, but it wouldn't go over 47mpg.
To be honest I was shocked and very pleased with the results, when I read that folks were getting in the early forties, I didn't really think it was possible!
So our Z4's are not just fast, fun, and good looking, there pretty efficient too when need be!!

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What a boring journey though, perhaps a bit quicker next time

[Marlon]

Great write up - CC was my most recent mod and its great for resting the right leg on long motorway journeys.
As for average mpg, I'm getting 26 at the moment but that is mainly short commutes. I managed 46mpg on a 250 mile trip last year before CC installed.

[1000rr]

Getting 34mpg ave over 400 miles, mixture of urban and town driving, hardly any motorway.

[RyanB88]

Had my zed about a week and averaging around 30mpg. If you cruise at 60 it does do over 40mpg though which I'm very imprsssed with!

[Chris_D]

just a word of caution - cruise will actually give you worse mpg than prudently governing the throttle yourself on a long trip. not by much but i think it has something to do with the way it's always 'on throttle' unless going down a hill etc.
my findings at least. but couldnt do without cruise!

[Mr Tidy]

I have cruise on mine, but only usually use it when there are average cameras.

If you don't mind variable speed you can do much better on economy with it turned off - just let speed build up downhill and let it drop a bit uphill. My cruise can seem a bit "brutal" with acceleration going uphill.

Since I had a new battery last December and averages got reset I've only done about 700 miles, but average mpg is on 32.1 (average speed is on 38.2 mph)!

I just can't seem to drive my Z4 slowly for some reason.

[tominator]

I have cruise on mine, but only usually use it when there are average cameras.

If you don't mind variable speed you can do much better on economy with it turned off - just let speed build up downhill and let it drop a bit uphill. My cruise can seem a bit "brutal" with acceleration going uphill.

Since I had a new battery last December and averages got reset I've only done about 700 miles, but average mpg is on 32.1 (average speed is on 38.2 mph)!

I just can't seem to drive my Z4 slowly for some reason.

Too be honest I really struggled driving it with the CC on for the entire journey home and going so slow
It took me a couple of mins over 2hrs when normally I can do it in 1hr 20mins.
At least I now know how efficient it can be, from now on though back to normal driving as it was intended.....fast

[Mr Tidy]

At least I now know how efficient it can be, from now on though back to normal driving as it was intended.....fast

You know it makes sense!

[DaveZ4richardson]

I have been out today and covered 230 miles on A class roads including dual carriageway, I have achieved 37mpg overall and I certainly didn't stick to speed limits when roads were clear. Average speed for whole journey was 45 mph using cc at every opportunity, that's including driving through villages at 30mph at times. Still more than happy with that mpg and know I can get better if I tried but would smile half as much lol.

[Ducklakeview]

Mine averages around 19-20 mpg during my normal spirited town driving.

However last weekend I did just on 850 miles, about 100 of which were 50mph ave speed check, the rest mainly cruise set to a gps indicated 79mph. Average speed over that distance was just on 58mph and mpg was 34.2...

I don't drive any of my vehicles for economy..

Mike

[paulgs1000]

Never had the patience to try a long trip at 60 in my 3.0si but that's brilliant mileage - just shows what's possible if you want or need it.
Being able to transit to a run at such mpg was a real boost to si ownership but you'll see it plummet when you're hooning

[scott202]

just a word of caution - cruise will actually give you worse mpg than prudently governing the throttle yourself on a long trip. not by much but i think it has something to do with the way it's always 'on throttle' unless going down a hill etc.
my findings at least. but couldnt do without cruise!

I thought I was going mad when I discovered this! Glad I'm not the only one.

Since installing CC I've struggled to match my best MPG readings. It's a small price to pay though for the convenience, and I didn't buy a Z4 because I thought it would be super efficient.

[mmm-five]

I can get 34mpg in the M if I reset it and drive 20/30 miles between traffic at less than 70mph.

But, most of the traffic I'm in (even motorway stuff) is too stop-start to get a great MPG.

My overall average (according to Fuelly) is 26.9mpg, which isn't bad when you consider that it includes all the fuel used on the track too!

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Very rarely use the cruise, except for average speed zones, as the traffic is not smooth enough. Did it once on the way back from the Ring (Dover to Liverpool leg), and the combination of steady revs noise, darkness and a very long day meant I was about to drop off. So I stopped for 30 mins, had a coffee & a walk and came off the motorway (just after Brum) and drove the remainder of the trip via the smaller roads through Wales.

I also notice that CC brakes the car when you're going downhill (to keep at the speed you've set), and then has to accelerate to maintain the speed up the other side of the hill. Whereas I tend to let it 'overspeed' on the way down, but keep my throttle position the same so that it makes it up the other side without having to change from the 'perfect' throttle position.

The best long-distance MPG I've ever got (tank to tank, not OBC) was from Tesco in Ashford, Kent to Aral in Adenau via the Ring entrance, where I got 32.5mpg and filled up just after (2-3 miles) the fuel light came on.

I used to do a whole down/back leg on one tank, but started filling up at the half-way point so that I wasn't just sitting around a petrol station for the other cars to fill up, and also so I didn't have to worry about being stuck in a motorway accident and having to take a cross-country, twister, slower route.

[blackabbot]

I've just had a run out to Barmouth from Kinmel Bay today a round trip of 133miles just on A roads my max readout was 47mpg in a 2.0i sport
So to achieve that readout in a 3.0 is amazing

[Mr Tidy]

I have cruise on mine, but only usually use it when there are average cameras.

If you don't mind variable speed you can do much better on economy with it turned off - just let speed build up downhill and let it drop a bit uphill. My cruise can seem a bit "brutal" with acceleration going uphill.

Since I had a new battery last December and averages got reset I've only done about 700 miles, but average mpg is on 32.1 (average speed is on 38.2 mph)!

I just can't seem to drive my Z4 slowly for some reason.

Now 850 miles since the new battery - average mph has gone up to 39.2, and average mpg is up to 32.8! Obviously just need to go faster!