Official Fuel Economy Thread (formerly Highway economy).

[Arctra]

Yeah, it definitely sucks some power from the engine. Sitting idling at traffic lights with Tig in neutral and no aircon it reads 0.6L/Hr, in drive with no aircon or in neutral with aircon it reads 0.8-0.9L/Hr, and in gear with aircon it reads 1.1-1.2L/Hr. So it seems to sip about 0.2 to 0.3 L/Hr more with the aircon on when in idle.

[jimbomort]

11-12 really isn't that bad in heavy stop/start traffic. Aircon defintely makes a diff, especially where idling a lot in traffic, but generally no where near as much as your driving style etc. You probably already know this, but just in case some thoughts if they help. We are in a country town, so not a lot of lights and more scope to maintain momentum with some anticipation, but I regularly get down into the 8's in short trips into town and back. Have got into the 7's going across town

If you really put the foot down, you will see the current fuel consumption climb up to 50l/100klm! 20-30 is almost par for the course with any kind of acceleration in 2nd. Of course these are for short periods but in stop/start can have a big impact. I get into third and fourth pretty quickly where I dont need to accelerate much (from 30klm/hr or even less in 3rd and from 45-50 in 4th which is quite OK for the car and gearbox as long as you dont ask much from it at low revs). Of course this can be harder in traffic.

stop start driving, especially if using the accelerator and brakes a lot, will kill fuel economy. For fuel economy momentum is your friend and so is full engine braking (ie coasting with your foot off the accelerator). Under those conditions you will notice that the consumption is actually zero, which is not just a trick, it actually is because most modern fuel injected motors cut off the fuel supply altogether in such conditions. And in a high gear you will also coast longer or even accelerate going down a hill while using no fuel at all.

So more you can do to anticipate traffic to reduce avoidable acceleration and braking and maintain your momentum the better.

There are plenty of good sites on economical driving if you are interested, Greenfleet have some good tips or just search on google.

[marcsamus]

Picked our 125 up from Melbourne on the weekend and drove back to Brisbane. Got an average of 8.6L/100KM. Pretty happy with that when you figure in a couple of foot flat to the floor overtaking 2 trucks in a row manuvers

[Arctra]

That's not bad, but I can better it

We just did out trip from Port Macquarrie to Gold Coast today and managed to average 6.3L/100km's. Was very impressed with that given there was some spirited foot-flat accelerations to overtake slow vehicles. I thought they'd spoil the economy a bit, but wasn't bad.

BTW, Anyone travelling around the Port Macq area beware. We spotted about 8 cop cars and 6 cop bikes pulling people over within the first 100km's of our trip.

[jimbomort]

Picked our 125 up from Melbourne on the weekend and drove back to Brisbane. Got an average of 8.6L/100KM. Pretty happy with that when you figure in a couple of foot flat to the floor overtaking 2 trucks in a row manuvers

congrats on your 125, no doubt you have seen the perfor/tuning thread re potential to increase the power and fuel efficiency of the 125 even further .

I have been very impressed with the fuel efficiency of the 125. As the engine beds in with an economical driving style, you will find that the fuel economy of the 125 will just get better and better (see below, ours has done 8500km now).

On a recent trip in our 125 up to Brissy I averaged an incredible 5.8 l/100km. Mostly hwy, but some suburbia. Amazing fuel economy for a petrol - almost too good, perhaps an MFD glitch, we'll see if repeats. There was a southerly blowing so a tail wind on the way up, but hell it wasn't exactly a gale and amazing either way. This was stock (my car now has APR stage 1). These figs were with steady cruising at 100km/hr, mostly using cruise control.

On the trip back (remapped to APR stage 1) not as good, albeit still only 6.5 l per 100 and that with a head wind and probably more aircon. I've done 6.5 a few times now, so have confidence in that, will see if those high 5 figs repeat. Regularly in the 6's per 100km is possible on longer trips in the 125 and with the remap you have the capacity for low 6's for 0-100 acceleration as well!!. Gotta love the Tig. On yeh baby

[BLWNHR]

Got an average of 8.6L/100KM.

...managed to average 6.3L/100km's.

Is this working it out properly (km travelled and litres at the pump), or using the in-dash display?

[Transporter]

Is this working it out properly (km travelled and litres at the pump), or using the in-dash display?

In dash display is somehow optimistic.
I found this as more acxurate:
Fill up the tank, reset trip meter, refill tank when it is down to 1/4 tank or less, (L used / km from trip meter) x 100 = L/100km

Here is nice software that will do it for you (Car organizer)
http://www.liqui-moly.de/liquimoly/w..._eng_home.html

[jimbomort]

In dash display is somehow optimistic.
I found this as more acxurate:
Fill up the tank, reset trip meter, refill tank when it is down to 1/4 tank or less, (L used / km from trip meter) x 100 = L/100km

dont necessarily disagree MFD may be wrong (especially noting my 5.8 in the petrol above), but I'd question whether the alternative proposed is necessarily more accurate. It is how much fuel you used, but with its own and potentially significant error margin. Unless you fill the tank to the exactly the same level each time you could easily be roughly 2 litres up or down either way (ie for 2 litres over - 1 litre 'under' at last refill, 1 litre 'over' when refilling to get litres used or vice versa)

You could stop when the pump stops each time, but doubt that is very consistent especially b/w different fuel suppliers and stations.

Does anyone know a reliable means of filling the fuel tank to the same level other than at the same pump at the same filling station to the same 'point', if indeed that works?

[Transporter]

dont necessarily disagree MFD may be wrong (especially noting my 5.8 in the petrol above), but I'd question whether the alternative proposed is necessarily more accurate. It is how much fuel you used, but with its own and potentially significant error margin. Unless you fill the tank to the exactly the same level each time you could easily be roughly 2 litres up or down either way (ie for 2 litres over - 1 litre 'under' at last refill, 1 litre 'over' when refilling to get litres used or vice versa)

You could stop when the pump stops each time, but doubt that is very consistent especially b/w different fuel suppliers and stations.

Does anyone know a reliable means of filling the fuel tank to the same level other than at the same pump at the same filling station to the same 'point', if indeed that works?

Hmm....then, more accurate way would be the long term fuel economy. Unless you want to drain the tank dry and measure the fuel you put in, drive as long as you have the minimum fuel in tank then drain it again to measure the remaining fuel. That will give you very accurate number. I like the long term fuel economy better.

[jimbomort]

Hmm....then, more accurate way would be the long term fuel economy. Unless you want to drain the tank dry and measure the fuel you put in, drive as long as you have the minimum fuel in tank then drain it again to measure the remaining fuel. That will give you very accurate number. I like the long term fuel economy better.

agree, and a good test would be too compare the longer term value on the MFD over 4-5 tanks. Problem for me is I always drive more economically than my wife (well almost always) and she drives the car a lot during the week, so wont help me with getting a sense of whether the really good economy figures I have managed are accurate. No matter down to Sydney and back next week, so a good chance to check out the accuracy of the MFD then, hoping to make it to Sydney(about a 770km trip) on one tank with plenty to spare, which if we average in the mid 6's will do.

Is anyone else doing mid 6's on longer trips in their 125's?