Better Mpg

[Guest]

Not sure why this is happening, as Summer MPG was not this good. Last fuel up on Fuelly was 60mpg, and listed as a high point in the fuel ups -although there was one other 60mpg event earlier this year. Today, after taking the details at Sainsbury's and noting them on Fuelly, it has gone up to 61.3mpg! I am impressed, but not sure why this is so. We have the Winter tyres back on and I have been paying more attention to the tyre pressures than normal, so maybe this is the reason. We have been getting -according to the car computer at any rate- a regular showing in the low 60mpg range. On a long run recently I got over 73mpg, being stuck behind slow traffic on the A49 for most of the journey. So, anyone else got good mpg? I know Bob Kneale will have.

[craggle]

During the summer my dash read out was reading a fairly constant 45mpg on my iQ3, 1.33, engined, 6 speed manual car.

This was with my 205/45 17 Toyo T1-R tyres being run at 28psi.

I fitted the winter tyres back on it a couple of weeks ago and already the readout has gone back to 49-51mpg. They are Dunlop SP winter Sport tyres in 175/60 16 size and are being run at 32psi all around.

The wider tyres make a big difference I guess to rolling resistance.

Craig.

[Grumpy Cabbie]

There are always slight variances when filling up and calculating the way you are. It's the long term average that makes a difference. I guess warmer fuel takes up more space? The garage might not be entirely level at one pump than the other. Too many variables.

[MarkyPancake]

My iQ3 auto with OEM tyres always got better mpg in the warmer months compared to winter.

[Cyker]

Mine's been all over the place due to variations in driving; My mostly-urban tanks have been roughly 61-62mpg but I got a 67mpg on this last tank due to little over a quarter of the tank being used to get me to Brummy-land and back

Not bad considering I'm driving in a decidedly un-eco-friendly way at the moment!

[Guest]

Well, the bad news is that the car is now giving less mpg, and I am assuming it is down to the poorer weather. Yep, lots of factors affect mpg on all cars, and I guess that is why the tests done on new cars have little to do with real driving conditions. They needed something to even out the results and chose what we know of today for economy figures that mostly we cannot achieve on the journeys we take.

Variables, word for the day.

[Guest]

Okay, I am officially not happy. Last Fuelly entry tells me our mpg has dropped to 50.4! As we say around here, WTF? I checked the tyre pressures (I keep a close watch on them, checked at least once a week) today and adjusted them, so will be looking very closely at our next fill up. Our driving habits and routes have not changed, although obviously the weather has. Since we've had the car, changes have never been by this much. If no improvement, or dare I say it, worse results, then it's going in for a check-up. Possible it could be the air filter, as they do seem reluctant to change them. However, it was serviced recently so...

[Grumpy Cabbie]

Resistance on wet roads affects mpg's surprisingly highly.

Keeping tabs on mpg's is quite a Prius thing in the US and there are drops of about 5% with wet/damp roads, increasing on significantly wet roads and raining weather. Then there's the cold air and the car struggling to warm itself to run efficiently, especially if you have the heating on highish.

Then I guess things like cold side walls of tyres could make a small effect too?

One thing to remember is that a 5% here or 2% there loss in mpg's is noticed on a 60 mpg car. Similar losses in a 30 mpg car are not.

[Cyker]

What is your route?

Routes that have lots of trafficy bits will be especially punished in the winter as the engine doesn't get a chance to warm up and will shed a lot of heat.

Mine has a fast A-road part in the middle which seems to be what's keeping me over the 60's (At least so far!).

That and my experimenting with harsher acceleration seems to be doing pretty well! I have a theory that the harder acceleration is generating more heat faster than it can be shed, plus it's known that most engines are more efficient under more load.

Once I hit the speed limit (Which is usually just after I've gotten to the other side of the junction ) it's into coasting mode which is obviously not using any fuel; This is contrasted with gentle acceleration which only warms the engine a tiny amount, much of which will be lost to the cold air, and is burning fuel for that whole time, whereas I use a load of fuel for a brief moment at the beginning and then none for the duration of the coast.

The other major saving is when I do hit traffic, I hang back instead of sticking to the **** of the car in front (like every-smegging-body else seems to do! ) - It's quite hard to resist the temptation to follow the car in front but I'm getting damned good at forcing myself to hang back and just roll, letting the gap in front grow and shrink as the car in front shoots off, brakes, shoots off - Meanwhile I haven't had to touch the clutch or brakes once ;)

Quite pleased with the results so far; The last two tanks my ickle diesel Yaris ran were 67 and 63mpg

The Mk1 D4D Yaris is a damned good car :D

[Andy Kay]

Could the temperature and density of air being inducted into the engine affect burn efficiency?

[Guest]

Another update after a fuel stop at Sainsbury's today. This is after I added the fuel up to Fuelly just now- Fuel-up Added - 58.6 UK MPG, Details: MPG: 58.6 Miles: 193.6 Litres: 15.02 Price: £1.13/Litre Total: £16.96. Clearly is a big improvement on the last fill up of 50.4mpg. This result will allow me to sleep at night again. Keep on keeping on

[Guest]

What is your route?

Routes that have lots of trafficy bits will be especially punished in the winter as the engine doesn't get a chance to warm up and will shed a lot of heat. Mine has a fast A-road part in the middle which seems to be what's keeping me over the 60's (At least so far!). That and my experimenting with harsher acceleration seems to be doing pretty well! I have a theory that the harder acceleration is generating more heat faster than it can be shed, plus it's known that most engines are more efficient under more load.

Once I hit the speed limit (Which is usually just after I've gotten to the other side of the junction ) it's into coasting mode which is obviously not using any fuel; This is contrasted with gentle acceleration which only warms the engine a tiny amount, much of which will be lost to the cold air, and is burning fuel for that whole time, whereas I use a load of fuel for a brief moment at the beginning and then none for the duration of the coast.

The other major saving is when I do hit traffic, I hang back instead of sticking to the ubik of the car in front (like every-smegging-body else seems to do! ) - It's quite hard to resist the temptation to follow the car in front but I'm getting damned good at forcing myself to hang back and just roll, letting the gap in front grow and shrink as the car in front shoots off, brakes, shoots off - Meanwhile I haven't had to touch the clutch or brakes once ;)

Quite pleased with the results so far; The last two tanks my ickle diesel Yaris ran were 67 and 63mpg

The Mk1 D4D Yaris is a damned good car :D

Well, we take various routes -like everyone else I guess- to different places, and traffic flow is usually pretty good. There has been the odd occasion when it has been bad, but lately okay for traffic. We try not to travel when the Mums and Dads are transporting their kids to and from school, but you can't always plan for that when you're out shopping and time passes as you trudge around making positive noises to your wife/partner etc as they spend an age looking at stuff they don't want or will not buy. Mostly on any route we take -if in to Wales or deeper into Shropshire- there are rural roads. For Shrewsbury this is about 13 miles, Welshpool is about 5 or 6 miles, and Bishops Castle is all rural roads at 24 mile return journey.

Tractors do tend to leave a lot of crap on the roads and so there is an issue for that concerning traction. Having once sat behind a tractor -and not able to get past due to oncoming traffic and bends- I was unlucky enough to get stuck behind once, it was shedding clods of earth for over a mile! Dirty b'strds! Now, a gripe of mine- If a truck or other vehicle driver loses part of its load on the road, they can be fined, but not Farmers for some reason, who, particularly for bike-ists of the pedal and motorised kind is pretty !Removed! dangerous. The same goes for when they do the hedge cutting. It is essential as they grow quite quickly, but come on, someone must have thought about a device to sweep the cuttings at least to the side of the road?

I tried your speed up quickly driving before when we had a 2.0 Auto Mondeo, and it was better on fuel that way; being an auto it coasted well up to junctions and lights. I still do that now, coasting, in gear, as we have a lot of hills around here, especially on the Welshpool route. My wife copies my driving style as she too wants to get the best economy from our car.

[Guest]

Update- Last fill up was at 61.2mpg -according to Fuelly. I am quite happy with that.

[Guest]

Another update, 59.3mpg after filling up at Sainsbury's again today. Good but not as good as the last fill up.

[sparrow2]

I have a 59reg IQ3. I keep the tyre pressures at 33psi at the front and 32psi at the rear as it recommends and check them each week. I have had the car from new and never modified it at all. The tyres are the original on the back but have been replaced twice on the front with the original make. I drive very carefully in built up areas but do accelerate quite briskly on main roads. I find I get better consumption in summer than winter on average. I track my consumption with Fuelly. Last year my best month was July at 47.8 mpg and the worst November at 40.2. In the entire life time of the car my worst fuel up was 34.8 mpg and the best 54.52 mpg. However I think individual fuel ups are misleading because the automatic cut off of the pumps is more sensitive on some than other so I suspect the tank is not always filled to the same amount.

[CPN]

...and is exactly why I defeat the pumps' auto cut-outs by pulling the nozzle out far enough so I can actually see the petrol going in after the first cut-off. Makes for a slow last couple of litres but at least I know exactly where I am filling the tank to every time. When I say "neck to neck", that's exactly how I fill my car each time so that my calculated figures are as consistent as possible. I should add that I've never spilled a drop! ;)

[Andy Kay]

I have a 59reg IQ3. I keep the tyre pressures at 33psi at the front and 32psi at the rear as it recommends and check them each week. I have had the car from new and never modified it at all. The tyres are the original on the back but have been replaced twice on the front with the original make. I drive very carefully in built up areas but do accelerate quite briskly on main roads. I find I get better consumption in summer than winter on average. I track my consumption with Fuelly. Last year my best month was July at 47.8 mpg and the worst November at 40.2. In the entire life time of the car my worst fuel up was 34.8 mpg and the best 54.52 mpg. However I think individual fuel ups are misleading because the automatic cut off of the pumps is more sensitive on some than other so I suspect the tank is not always filled to the same amount.

I have a 10reg iQ3 and my fuel consumption is pretty much in line with yours. I'm also on Fuelly -- we seem to be a select band on Fuelly but it's a useful site to compare fuel consumption amongst us even so.

[byzantian]

I have recently bought a 1.0 VVt IQ that is around three years old and has done around 18,000 miles. I'm disappointed with the MPG as the best it is returning is 42mpg - all of which is in town. Is this the best i should expect from the IQ?

[Grumpy Cabbie]

See replies in your original thread

[Andy Kay]

I have recently bought a 1.0 VVt IQ that is around three years old and has done around 18,000 miles. I'm disappointed with the MPG as the best it is returning is 42mpg - all of which is in town. Is this the best i should expect from the IQ?

Don't know about the 1.0 but my 1.3 seems to be returning high forties in summer and low forties in winter. I'm not unhappy with that, coming down from a 2.0 Mazda TS2 that returned around 20mpg.