Not really insane, you are driving at speeds that are beyond those which will achieve those figures.
Question about engine size and fuel economy
- Thread starter kissenger
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Not really insane, you are driving at speeds that are beyond those which will achieve those figures.
The only use you can put these official fuel economy figures to is comparing one car against another, but never actually expect to achieve the quotes figures for all the reasons others have outlined above.
As a side note I have found that, in general, the quoted figures for petrol engines cars seems to be closer to real world than that of diesels. I don't have any empirical evidence of this, it's merely my own experience.
As a side note I have found that, in general, the quoted figures for petrol engines cars seems to be closer to real world than that of diesels. I don't have any empirical evidence of this, it's merely my own experience.
I managed 65mpg from a 1.6 TDI Octavia recently. Try harder
Could I still get close to that with mine being an estate?
I never expected to get 80mpg, but I was hoping for 65+. I have wondered if it's my driving style. I'm coming from a Prius, which is an automatic, so I'm not used to manual, let alone diesel. I tend to up-shift gears slightly quicker than the dash requests -- maybe that's part of it.
I know I could get close to 80 if I just went at 60mph on the motorway but that to me is too extreme. 70 is what you should be driving at on the motorway.
Indeed.
My vehicle of choice is a 1995 LC80 4.2TD Land cruiser
Mostly, I get what I deserve for a 2.5ton vehicle with a massive old school truck engine coupled to an automatic gearbox and permanent 4WD.
And yes, that is 18-22 MPG
BUT....!
On a long run, (SW Surrey to Yorkshire and back)
I have recorded 37MPG!
Hypermiling can be quite fun, And even not, very financially rewarding.
(Surprisingly, for long journeys, the LC is actually one of the more economical vehicles I have ever owned. Only the R5 campus was better)
Before going onto the rolling road a coastdown test is carried out to measure the wind resistance of the vehicle against speed and this is factored into the control system of the rollers to provide the wind resistance. Whether the coastdown values are realistic is another matter.
I managed 65mpg from a 1.6 TDI Octavia recently. Try harder
I recently had a 2.0TDI Octavia for a 320ish mile round trip which included a couple of days of city commuting and heavy traffic on the M42 (both directions). It easily managed 71mpg so not sure what you were doing.
That probably is a big part of it. Staying in the highest gear possible is usually best. As a diesel it's probably fairly happy to run along at low revs.
That means shifting up early as possible, but still shift down when the extra power is needed (flooring it with the revs really low isn't going to do any good - better to get back up to the peak torque region).
Trueplus the big hills around here don't help.
For every uphill there is usually a downhill where you don't have to use any fuel....
Hypermiling is great fun, but does tick off all the impatient gits behind you
It is funny though when you see them brake in your rearview and you just maintain all your speed through a corner, approach a roundabout and they haven't planned ahead and you go through it sans brakes and they drop back 100 feet
It's all about speed and driving style. I once tried a total economy run for ~6 mile. Clear roads, engine already up to running temp and managed 52MPG out of an R56 Cooper S. Lots of coasting involved, not slowing much for wide open roundabouts, all the traffic lights went my way, etc. Usual driving it's about 35MPG.
It's all about the driving style! If you concentrate and plan ahead, don't mind getting over taken by hgv's and turn off all creature comforts you can really change results. The a180d sport I've got usually averages around 68-70mpg per tank on my commute, to test and see what could actually be done I drove like my granny stole it in economy mode with no hard acceleration and for a 54 mile round trip commute it tipped the onboard computer at 99.9mpg. They were probably the most difficult and draining journeys I've ever driven!
I recently had a 2.0TDI Octavia for a 320ish mile round trip which included a couple of days of city commuting and heavy traffic on the M42 (both directions). It easily managed 71mpg so not sure what you were doing.
Bah! You were doing 56 behind lorries, weren't you?
I always sit at 70mph for my hire car MPG tests!
I usually get between 19 and 21 mpg to a tank, so just be happy
Same.
The EPA figures are pretty accurate though - 11-15.5 l/100km and I get very close to 11 when doing just "highway" mileage, and average around 14 l/100km (20mpg) day to day (mostly in town).
We were discussing this the other day. All things being equal (same engine tech, gear ratios, vehicle weight and terrain etc) I'd assume fuel consumption is fairly linear despite engine size. i.e. a 2L engine needing to rev to 3000rpm to sustain 70mph will use the same amount of fuel as a 4L engine only needing 1500RPM?
We were comparing three vehicles (different makes, sizes etc, but all petrol) and looking at RPM at a set speed (around 70mph) and the rpm differences were fairly significant. One vehicle rarely goes about 2000rpm (sits at around 1200-1700 usually) for anything but flooring it, whereas the other spends its time at around 3000rpm just around town and the least fuel efficient sits in the middle (middle sized engine) and sits at around 2500rpm
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Soldato
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Same.
The EPA figures are pretty accurate though - 11-15.5 l/100km and I get very close to 11 when doing just "highway" mileage, and average around 14 l/100km (20mpg) day to day (mostly in town).
We were discussing this the other day. All things being equal (same engine tech, gear ratios, vehicle weight and terrain etc) I'd assume fuel consumption is fairly linear despite engine size. i.e. a 2L engine needing to rev to 3000rpm to sustain 70mph will use the same amount of fuel as a 4L engine only needing 1500RPM?
We were comparing three vehicles (different makes, sizes etc, but all petrol) and looking at RPM at a set speed (around 70mph) and the rpm differences were fairly significant. One vehicle rarely goes about 2000rpm (sits at around 1200-1700 usually) for anything but flooring it, whereas the other spends its time at around 3000rpm just around town and the least fuel efficient sits in the middle (middle sized engine) and sits at around 2500rpm
Interestingly in engineering terms the reason a smaller engine is supposedly more effecient is due to the "pumping loop" ie a big engine running at a low load will be "sucking" against the throttle obstruction, as engines theoretical effeciency is actually highest at full bore.
However when you try to translate this to the real world people want to go fast sometimes and a small engine obviously doesnt have the grunt unless your driving miss daisy, to get around this they turbo everything now so you have grunt when you need it.
Issue is, because people want to go faster they just floor it anyway so it defeats the purpose.
I'm not a fan myself, for simplicity's sake i'll take the fabia:
Mk1 was a 1.9 tdi at 100bhp, mk2 was the same from a 1.6 and the mk3 is the same again from a 1.4. now sure this means better theoretical effeciency, and the lab tests prove it, but what it means in the real world is you've moved from a relatively smooth power curve where its not that obvious when the turbo kicks in to an engne thats just dead until you give it enough welly then suddenly it takes off.
Soldato
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On the motorway? Enjoy those artics overtaking you as close as possible.
Really annoys me this, as you doing 60 forces large vehicles into the middle lane just to keep their momentum up and thus turning a 3 lane road into a 1 lane for 30 secs minimum, and repeatedly, until the truck(s) gets past.
Just to save a few precious pennies.
HGV's are speed limited between 52 - 56mph, doing 60 in most - certainly Volvo's & Scania's - will gain the driver an "over speed infringement" on his tachograph, not to mention you'll only exceed the limited speed on downhill sections - over run - when carrying a fairly considerable load weight.
So long as cars don't drop below an accurate 60mph (bearing in mind tachographs are calibrated whereas speedometers in cars aren't) then you shouldn't cause a problem to larger vehicles and still save a bit of juice,don't get me wrong, not much annoys me more than a car doing ~ 50mph especially when they usually speed up once the truck tries to pass them, but, should you bear in mind my points then your annoyance should be unjustified.
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Soldato
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My car (1.8 08 Ford Focus) Apparently gets 42.8mpg according to honest John. Over the past few tankfuls I've been driving as economically as i possibly could, and got three tanks in a row of 45+ mpg, and then had two tanks driving completely uneconomically and really short journeys where the car wouldn't even have time to warm up. Over those two tank fulls my MPG was around 36mpg.
I also did a bit of maths that said that if I did a 500 mile trip at 36mpg, it would cost me an extra £15 over if i'd have got 45mpg ..
I also did a bit of maths that said that if I did a 500 mile trip at 36mpg, it would cost me an extra £15 over if i'd have got 45mpg ..
Soldato
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HGV's are speed limited between 52 - 56mph, doing 60 in most - certainly Volvo's & Scania's - will gain the driver an "over speed infringement" on his tachograph, not to mention you'll only exceed the limited speed on downhill sections - over run - when carrying a fairly considerable load weight.
So long as cars don't drop below an accurate 60mph (bearing in mind tachographs are calibrated whereas speedometers in cars aren't) then you shouldn't cause a problem to larger vehicles and still save a bit of juice,don't get me wrong, not much annoys me more than a car doing ~ 50mph especially when they usually speed up once the truck tries to pass them, but, should you bear in mind my points then your annoyance should be unjustified.
I suspect a lot of cars doing 60 by there speedo is about 56 actual anyway, i know mine is.
Diesels don't have throttles.