er, this isn’t a diesel forum, it’s the 2012+ Panda forum (but members are, of course, welcome to comment on specific engines and thoughts relating to such engines (which may - or may not - apply to other engine types)
General Is ‘Economy Driving’ Worth It?
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General Is ‘Economy Driving’ Worth It?
An engineer/engine expert I encountered while learning to fly compared aero engines with car engines, he made the argument that the reason aero engines live for so long with many engines fitted to aircraft from the 50s 60s 70s and 80s still largely being the originals, is that aero engines do not change speed very often.
For example on a climb out you might set the throttle at 2200rpm and hold it at that level till you finish your climb then reduce it back to 1700rpm, while cruising for hundreds of miles, then at the end of your flight slowly reduce down to idle for landing, there is no one constantly jabbing at the throttle, no hard acceleration no forces put through the engine from rapid hard braking.
Car engines are subject to all sorts of abuse.
One think I would say about some of the comments above is that water pumps these days do not all operate all of the time. The pump in my car can be switched on and off effectively, so which was an unpleasant discovery and bill when I asked for the water pump to be replaced with the cam belt.
As pointed out oil pressure is only proof of resistance in the system, a blocked oil way to one bearing shell will still show good oil pressure but will also make the engine no better than a boat anchor pretty quickly.
I would also argue that in terms of acceleration it is not technically possible to “abuse” an engine in any standard road car.
So the only way you could “abuse” and engine is to down shift into the wrong gear and exceed the Rev limiter…. I’ve never known a case when that ends well, though I would say that using an engine properly does tend to result in a better running engine.
I just want to check the comments about EGR coolers, as I understand these are cooled by the engine coolant, so if you are running and engine at high revs any EGR coolant effect will result in increased coolant temps and more heat for the cooling system to shift. Potentially increasing under bonnet heat and the heat in any hotspots.
For example on a climb out you might set the throttle at 2200rpm and hold it at that level till you finish your climb then reduce it back to 1700rpm, while cruising for hundreds of miles, then at the end of your flight slowly reduce down to idle for landing, there is no one constantly jabbing at the throttle, no hard acceleration no forces put through the engine from rapid hard braking.
Car engines are subject to all sorts of abuse.
One think I would say about some of the comments above is that water pumps these days do not all operate all of the time. The pump in my car can be switched on and off effectively, so which was an unpleasant discovery and bill when I asked for the water pump to be replaced with the cam belt.
As pointed out oil pressure is only proof of resistance in the system, a blocked oil way to one bearing shell will still show good oil pressure but will also make the engine no better than a boat anchor pretty quickly.
I would also argue that in terms of acceleration it is not technically possible to “abuse” an engine in any standard road car.
So the only way you could “abuse” and engine is to down shift into the wrong gear and exceed the Rev limiter…. I’ve never known a case when that ends well, though I would say that using an engine properly does tend to result in a better running engine.
I just want to check the comments about EGR coolers, as I understand these are cooled by the engine coolant, so if you are running and engine at high revs any EGR coolant effect will result in increased coolant temps and more heat for the cooling system to shift. Potentially increasing under bonnet heat and the heat in any hotspots.
The Panda Nut
Nutty about Pandas Infected by Panda virus and OPD
Eco driving long term, is a two edged blade. My Mrs' car which I was driving today, as its now the builders wagon for my daughters new house, was just awful. Slow sluggish and unresponsive. It does do good mpg as she drives it gently, and whatever anyone says its better long term to keep the revs down if you want the engine to last, while not labouring things and stressing out every bearing in the drive train. However these VVT units need opening up every so often, to give them an Italian service. After a well laden trip along the bypass today at significant speed for 10 miles the difference is tangible. I think the VVT actuator gets sticky if it doesnt open reasonably regularly. Ive told both my girls to use a few revs and hold the gears few times a week on a regular basis, at least to 4500 and when on a long to deliberately run in 4th at higher revs for a few miles, to balance the round town norm. Thrashing to 6500 rpm is not going to be good either, but the 1.2 Panda seems benefit from an occasional brief trip to the red line I suppose it makes the VVT do its.
I suppose its like all things, a balance and moderation is best.
The eco function on the TA Panda varies from one batch of cars to another, but does make some difference. Mine easily matches the 1.2 performance with eco on, and I leave the thing on - its default- most of teh time, not even thinking of it. Its great to grab another 20hp at the push of a button on hills or on busy roads where progress is required. Once up to speed the extra is not required so I switch off. Up to 50mph the car is more economical in eco on. Above 50 its less clear and having the power available but using a light right foot works well.
We have now four pandas, two are driven gently, one of those has a decent number of long runs thrown in, and one mainly local, One I suspect is driven briskly and mine is just driven as smoothly as I can with an eye to economy on long runs. So far I havn't noticed any difference in maintenance requirements, save the one given more stick eats more tyres and brakes.
The one driven gently and generally at low revs gets very yardy and needs giving a burst of speed to restore performance after 500+ miles of lethargy.
I used to drive fast and hard. It wreaked havoc with all the cars mechanicals, but less so than you might imagine. My company cars were all hammered all the time. I could tell when they were serviced and indeed when the cam belts were changed. Being driven vefast, but smoothly didnt seem to cause any issues.
Punchline is, that with modern engines it makes little difference, but an occasional brief thrash helps keep it all mving.
I suppose its like all things, a balance and moderation is best.
The eco function on the TA Panda varies from one batch of cars to another, but does make some difference. Mine easily matches the 1.2 performance with eco on, and I leave the thing on - its default- most of teh time, not even thinking of it. Its great to grab another 20hp at the push of a button on hills or on busy roads where progress is required. Once up to speed the extra is not required so I switch off. Up to 50mph the car is more economical in eco on. Above 50 its less clear and having the power available but using a light right foot works well.
We have now four pandas, two are driven gently, one of those has a decent number of long runs thrown in, and one mainly local, One I suspect is driven briskly and mine is just driven as smoothly as I can with an eye to economy on long runs. So far I havn't noticed any difference in maintenance requirements, save the one given more stick eats more tyres and brakes.
The one driven gently and generally at low revs gets very yardy and needs giving a burst of speed to restore performance after 500+ miles of lethargy.
I used to drive fast and hard. It wreaked havoc with all the cars mechanicals, but less so than you might imagine. My company cars were all hammered all the time. I could tell when they were serviced and indeed when the cam belts were changed. Being driven vefast, but smoothly didnt seem to cause any issues.
Punchline is, that with modern engines it makes little difference, but an occasional brief thrash helps keep it all mving.
Our cars don't have any easy life by any means...but warmed through you can pretty much do you want and unless you money shift it the engine and gearbox will be happy enough.
I spend all my earthly goods on suspension repairs and brake parts
I'm very much someone who will use all the horsepower I've paid for but not all the time and not when the car is cold. Otherwise unless the thing is vibrating at low revs or nutting the limiter I don't think they particularly care.
For economy I like a sharpish acceleration on to the cruise. At which point it'll be in the highest gear possible. The engine is most efficient at full throttle when it comes to transferring fuel into energy so no reason to take it easy until you've reached cruising speed and let it settle.
just remembered a ‘trick’ I used when I did a lot of motorway driving
- accelerate to above desired speed (mpg readout drops, but only for the few secs this took)
- then ease back throttle and watch readout climb to high mpg, car v slowly reducing speed, maybe a minute)
Repeat.
Because it’s all about averages. This way I could get low 40s in my Octavia 4x4. But it took effort and concentration, and not feasible on a busy motorway.
Some birds fly this way too - presumably to conserve energy/get more “mpg”! - eg green woodpeckers: 3 flaps (bird rises) then glide (bird descends) then 3 flaps etc
- accelerate to above desired speed (mpg readout drops, but only for the few secs this took)
- then ease back throttle and watch readout climb to high mpg, car v slowly reducing speed, maybe a minute)
Repeat.
Because it’s all about averages. This way I could get low 40s in my Octavia 4x4. But it took effort and concentration, and not feasible on a busy motorway.
Some birds fly this way too - presumably to conserve energy/get more “mpg”! - eg green woodpeckers: 3 flaps (bird rises) then glide (bird descends) then 3 flaps etc
I think people misunderstand egr, it's purpose is to dilute the oxygen with spent exhaust gas, meaning you can still keep good gas flow at proper revs, and cooler cylinder temps as there's less oxygen and fuel in there (as the argument was lower revs means lower combustion temps)
Also jet engines are vastly simpler in basic design to car engines. And piston aircraft engines are serviced and maintained to a higher standard than the typical car, not sure you can compare like fit like there either.
I'd read that recently as well, apparently as modern engines are most efficient at wide throttle openings, that it's better for economy to accelerate and slow down than to trundle along on part throttle.
Seems surprising to me, and a counter-intuitive way to drive. Did you find it worked?
I'm with you on this, in a 30mph zone I'll be in 3rd if there are potential hazards, only in 5th if it's a long clear stretch.
I ignore most of what I read, and find out for myself
If it's fly by wire throttle body and you punch the accelerator when under heavy load do you even get wide open throttle
I average over 60mpg, in a 1.2 60bhp, occasionally I go down to the high 50s and get upset with myself
Rarely use over about 1/4 throttle, most gains are by reducing throttle ever so slightly and letting the speed reduce ever so slightly over several miles, then build up the speed on down hill gradients where possible
Fair point. I'll admit to being a bit ignorant about modern car tech.
I was raised with some old-fashioned ideas like 'warming up' the car before setting off, or using 'direct top' to place less strain on gearbox internals.
Neither of which apply to my Panda. So I'm receptive to advice on what I should be doing differently. Especially if it saves fuel.
In my dinosaur brain more throttle = more fuel but I'm learning maybe it's not so straight forward with a modern ECU?
That it's better to accelerate quickly to your cruising speed?
I agree with you on the general fuel-efficient driving practices, when to accelerate and decelerate.
I've often thought it would be a good idea to have maybe a mile advance warning when approaching a village on a fast road so we can ease off gently rather than jump on the brakes.
I do that on roads I know, but then you get Audi-doodies up your chuff trying to accelerate hard towards a 30 zone
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Waze, the free satnav now gives you a 0.3 mile warning that you're approaching a 'reduced speed zone' -- generally fro 30mph areas but opcciasionally for some 40's too......I've often thought it would be a good idea to have maybe a mile advance warning when approaching a village on a fast road so we can ease off gently rather than jump on the brakes.
I do that on roads I know, but then you get Audi-doodies up your chuff trying to accelerate hard towards a 30 zone
My understanding is you are correct in terms of more throttle = more fuel.
But the engine is at its most efficient at converting fuel into movement at full throttle around peak torque. So as long as you aren't whanging it off the limiter or running consistently at high rpm where you suffer more pumping losses you will be using fuel quickly but it will also be getting the most movement out of that fuel. Once at speed maintenance takes the same amount of fuel.
Accelerating slowly uses less fuel in a given moment of time...but makes the period of increased fuel use of acceleration longer. I also understand there's a loss of efficiency associated with the partially open throttle blocking/altering air flow and reducing the amount of work a given amount of fuel does.
Of course waters get even more muddy...when you start talking about variable cycle engines, and hybrid systems and cars with "sailing" mode.
I used to do a lot of motorway driving for my job and I bought a new Octavia 4x4 saloon in 2002 (loved that car!) and found I was getting around 38mpg on long motorway journeys.
The company paid a fixed mileage allowance for business travel and required detailed records so I maintained a spreadsheet of all my mileage, petrol, distance, dates etc.
I also wanted to “make a profit”
I’m simply sharing the results shown by the data I gathered on my long distance motorway trips (realistically, the only roads suited for this technique) and when the motorways were running freely, enabling ‘constant speed’ motoring, I remembered the bird flights I’d observed and decided to experiment between “constant throttle” and the technique I described.
Mimicking a flight technique observed in solitary birds like green woodpeckers (formation flyers eg migrating geese use a different technique) worked for me - the best long distance mpg I recorded was just under 45mpg.
And remember, no creature exhibits a particular behaviour unless it conveys an evolutionary advantage - in this case, conserving energy (what we call “economy”)
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What possible evolutionary advantage could our strange proclivity for driving small, relatively unreliable Italian cars confer?
A strong sense of community through shared hardshipsWhat possible evolutionary advantage could our strange proclivity for driving small, relatively unreliable Italian cars confer?
That's interesting, makes sense. I have a tendency to build speed gently, but now I have an excuse to fully open the taps on the Panda
And hold on for dear lifeRight! Drive like a woodpecker it is
I think that's going to be my new mantra from now on. "To become the woodpecker you must think like the woodpecker." - ancient Fiat Forum proverb.
Just watch out for them trees
There's a lot of misleading information on the internet
Theory is all well and good, what happens in the real world is what counts
A carburettor isn't the same as EFI
Fly by wire isn't the same as cable
Petrol isn't the same as diesel
With the 1.1 or 1.2 gentle throttle movements is the way to go,
If you jab the throttle, it's brains will enrich the mixture, if an injector has already shut off it will open for a second firing, 100% Throttle will also enrich the mixture
Its deffo the driver that makes the biggest difference as my car does not get the same MPG when the GF drives it
In the old day some cars were fitted with a vacuum gauge, which was handy, if you saw the vacuum go down you knew it was time to change down a gear, you can do the same with the trip computer if it's set to display current MPG
Theory is all well and good, what happens in the real world is what counts
A carburettor isn't the same as EFI
Fly by wire isn't the same as cable
Petrol isn't the same as diesel
With the 1.1 or 1.2 gentle throttle movements is the way to go,
If you jab the throttle, it's brains will enrich the mixture, if an injector has already shut off it will open for a second firing, 100% Throttle will also enrich the mixture
Its deffo the driver that makes the biggest difference as my car does not get the same MPG when the GF drives it
In the old day some cars were fitted with a vacuum gauge, which was handy, if you saw the vacuum go down you knew it was time to change down a gear, you can do the same with the trip computer if it's set to display current MPG
FWIW, I’ve just completed a 1500 mile road trip in my 2020 15K miles TA, from the north of England to Austria and back. For almost all of the trip ECO was on, climate was off, and I was driving at steady motorway speeds on E5 petrol. I was expecting to see an improvement on the upper 40s mpg I get “around the doors”, but the indicated average for the trip barely moved: just 50.
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Not forgetting the weight factor in fuel economy. So get rid of the passengers, the spare wheel, the full petrol tank. And go on a diet
Interesting - thanks
mpg is all about the average, and “steady speed” may not deliver the highest average
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Interesting data point. My TA 4x4 2013 does maybe 38mpg running around home and with Mrs Panda eyes driving. I can get it into the low 40s without too much effort but it seldom does long runs so hard to know if it can be bettered. E5 definitely improves things. I don't indulge the ECO button! Of course the fuel mapping may have changed over the years too(?)
