MPG - I DON\'T believe it!!!!!!!!!!!

[zevans]

7 x 20 min sessions at Cadwell, at 2 minutes or so a lap, 2.25 miles long, makes ~150 miles out of just over a tank, so call it 13 gallons.

11.5 mpg then

[Ianmcurtis]

^ Now u r talkin\' Zack !! ;-).

[zevans]

Must of been that big hill in 4th that did it... (think of Laguna Seca, quite similar!)

Nearest petrol station was one of those "UK" jobs, tank was filled by a guy chewing on a bit of straw. I half expected to see two people with banjos on the veranda.

[Ianmcurtis]

^ I know cadwell and the \'mountain\'. Done that on my old yamaha thunderace back in \'98, wicked track. Done brands indi, silverstone too on the bike.

[Spectre26]

I remember a while back reading a post by zevans when he mentioned that the 8 had to be driven hard before you hit a track in order to "get the ECU into the right frame of mind". Think he said it was something like your ECU learning what type of driving u are doing. So if u r driving hard and "sporty" then it will assume a more sporty but less fuel efficient mode.

This in mind, does that mean if u want max fuel economy u have to consistantly drive the 8 in a fuel concious way? Because i dunno about any of u guys out there but i definately can\'t drive fuel conciously for the period of which a full tank lasts. :evillaugh

[zevans]

Well, it takes a couple of track sessions to get into track mode, so presumably it\'d take 50 miles or so to get into full fuel-econ mode...

However, I have also had a conversation with the local technician, and he reckons my car is quicker by far than any of the others he services. So there are long-term effects of not using the revs, by the sound of it - ie everything gets full of crap and it\'ll never perform to full spec!

There\'s not that much in it tho, I\'m just unusually sensitive to cars and their foibles, I have so concluded this year...

[Spectre26]

Attended the prodrive day on the weekend gone. And part of the "lessons" u get told on the day is on the RPM band in which the 8 is most efficient. I\'ve forgotten what exactly it is but roughly its after 3k upto 5k. And we were told to keep it in a lower gear and not always drive at the lowest possiable gear.

With this in mind when i drove home from prodrive back to Gatwick i programed the GPS to avoid all motorways so as to take the senic route. Started with a full tank and when i got home and pumped up back to full i\'d saw i had used 25 liters, except i had 160miles on the clock. roughly working out to 24MPG.

Now bear in mind that the closest i have ever been to this figure was by doing motorway driving. So hitting 24MPG on country lanes and only @ 10 or so miles on A-roads, it supprised me quite a bit.

During the drive i aimed to keep my needle as close to the 4k mark as possiable and never exceeding the 5k mark or going below the 3k mark.

Dunno what u guys think? be cool if this is correct and not a one off fluke.

[BlueAdept]

Don\'t get too excited, I\'ve got mine to do 320 miles on a 55 litre fillup.. that\'s 32MPG!

24 is pretty OK, but you\'ll find that as soon as you go over about 70, you\'ll be in a lower economy bracket, so A roads are actually more efficient if you stay in 6th for any length of time,...

The other weird thing, is that the engine seems to be more efficient the harder you drive it, so bursts of high power intermixed with coasting like you tend to do on a slightly twisty A road is pretty good also, even if you\'re really pressing on...

The 320 mile tank was following a friend home after he bought a classic car, he was crusing around 60-65 all the way on a motorway, and I wasn\'t able to use cruise (It\'s not perfect for economy driving) since he wasn\'t really going at a constant speed.  Since I could catch him easily, I wasn\'t worried about letting him get a little way ahead, so it was a 300 mile cruise taken gently at 60-65, probably in 5th rather than 6th for half of it...

Not that I really think about it these days, I just enjoy the car and normally get about 220-250 from a tank...

[Ianmcurtis]

As it happens following the Prodrive day, I filled up at 245 miles covered for the day and part of the the following Sunday. A real mixture of driving in there as anyone who\'s done Prodrive will appreciate, including the drive to/from.

[Spectre26]

Not that I really think about it these days, I just enjoy the car and normally get about 220-250 from a tank...

Ya know i think thats the attitude i should eventually take.

But what ya said about coasting and bursts of power does tie up with what i was doing. So i guess its something to bear in mind when driving the 8 but as mentioned above, it shouldnt be something to obsess over.

Just enjoy the ride  :driving

[dubber91]

most modern ECUs have a \'self learn\' aspect to them. For instance, many modern cars recognise the NEDC drive cycle on a dynomometer, and switch to best possible emissions. Other cars are really shifty like the BMW M3. This has two methods. First off if the bonnet is open (it should be on type approved tests) it switches to a non-descript emissions mode. Testing with the bonnet down, it immediatly starts chucking in fuel around the 1400 seconds after startup mark.....strangely this is the time it takes to conduct an NEDC cycle!
it trips em up if you tests back to back without turning the engine off though
Its the same for sports usage. ECUs often have 6-10 driver styles which it recognises and gives best pobbible fuel cons. For the first few, maybe somebody uses 1st through 4th a lot, say town driving, so it will switch to the most efficient fuelling regime.
The last styles are for the heavier footed of us.....these recognise various states of sports useage - the country lane mode all the way through to out and out sports/racing. Distinguishing between modes is very difficult for the ECU and thus many stay in one mode, until a certain number of repeatitions of a particular driving style are experienced, then changing over.
Its all very clever ****, and i dont know the exact in and outs of it....but interesting nonetheless!