For the real world average driver I reckon fuel economy has not improved significantly over the years. Lets remove the extremes to start with.
Take Humph with his 50,000 miles each year. 30 years ago he probably would have been driving a Cortina 2.0 and later a Cavalier 2.0. He probably would have got between 28 - 38mpg. 20 years later in a car with the same performance and size he can get 50mpg but only because he is driving a diesel.
Take me with my 9,000 miles pa. I was driving a Cortina 2.0 and a Cavalier between 20 - 25 years ago. Average fuel consumption was not much better than 22mpg. It is not worth me buying a diesel because of the low mileage I do, so I buy a petrol. Would I get any better economy from a modern car of equivalent size and performance. I don't think I would. Almost every car I have driven over the last 15 years has returned between 20 - 22mpg, irrespective of size, engine, make and performance. The only difference was a Peugeot 605 DT which gave me 30mpg and the Volvo XC90 D5 in which I am averaging about 25mpg.
What is the reason - is is the increased weight of the cars, increase in stagnant traffic or simple lack of inherent efficiency?
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Safety and emissions controls have conspired to make cars less efficient.
We now need 120bhp or so to drag a hatchback along at any speed.
I've not got the figures to hand, but I'm sure something like a Cortina managed with half that.
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>>I've not got the figures to hand, but I'm sure something like a Cortina managed with half that.
The original Golf GTI had 110bhp IIRC and was wonderful to drive - still is I should think.
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Petrol economy is notoriously compromised by catalytic converters, which can't work with lean burn - the fuel/air ratio is in effect fixed.
Cars are certainly much heavier - at least 50%? Tyres are often much wider than they need to be. Cars are more powerful, and when the driver uses that power profligately as many do, economy suffers.
On the plus side, engine efficiency aside, cars became much more aerodynamic in the 80s. I remember my first drive in a fairly low powered 2 litre Audi 100 being a revelation in comparison with a similarly powered Cortina!
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Well of course the portential for massive improvement is there if you take it. I see diesel as a legit choice to compare with petrol if the overall experience is a good comparison so for me....
25-30yrs ago I was usually running 2.0 mid-luxury cars (petrol of course as diesels were for lorries back then). With mixed town/rural running I'd probably be averaging 24-27mpg.
These days my C5 returns 50mpg and does everything else better than these earlier cars. So for me fuel use has halved.
It's brilliant.
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Let me compare my Landcruiser 80 series 4.2 diesel auto of 1993 vintage, and my newish D-Max pickup 3 litre CRD auto.
LC average - 27mpg
Dmax - 30mpg
LC nice long steady run - 30mpg
Dmax nice long steady run 31mpg
LC towing 3 tons- 24mpg
Dmax towing 3 tons 25mpg
Same power
LC has more torque and lower down.
Both auto
LC 1/2ton heavier
LC has worse aerodynamics
LC has done 220K miles, so isn't exactly in the prime of life.
So taking everything into account, the fuel economy hasn't really improved any. But there are many advantages to owning the more modern (Dmax) vehicle:-
The 4 cylinder engine sounds like a bag of nails
There's a million electronic engine bits to go wrong
High pressure pumps and injectors are ultra reliable, and cheap to fix if they go wrong
It doesn't tow anywhere near as well
It doesn't have a proper solid front axle
No front or rear difflocks
Less axle articulation
(Of course I'm being sarcastic)
All I can think is, what would something like a Dmax be like with a big proper old-school straight six engine in it? I bet it would do more mpg, that's for sure. The only downside is a bit more smoke.
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I like Dave's post, and if you want a replacement for the LC or an old school engine for the pick up, here is exactly what you are describing, still make 'em too as troop carriers.
www.tradecarview.com/used_car/japan%20car/toyota/landcruiser+70/3056431/
It's really in Diesels where the gains have been made, not so much economy though from the latest as the gadgets to reduce pollutants seem to be taking their toll, it's the power and performance available given the weight increases thats so impressive.
If we drove our modern vehicles at the speeds and acceleration our older cars were happy at we would see fantastic economy.
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wo wo wo, hold on just a cotton picking moment.
30 years ago, 2.0 litre cav or cortina, 38 MPG
I really dont think so. even on a run.
Heres a curve ball for the calculation.
We have *many* more bypasses, miles of dual carriageway, motorway. These will all conspire to improve MPG on a hourney despite what the manufacturers do.
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I reckon my current Vectra B 2.0 16v 125 bhp gives much the same cruising economy as my 1990 Cavalier 1.8 90 bhp ( carbeuretter) did - low 40s. Around town the Vectra drops to 33, I reckon the Cavalier dropped to 30. That is on the same routes, it's only 7 years ago that I was using the Cavalier.
I reckon there hasn't been much improvement in mpg for light footed motorway cruising in similar sized cars, but better economy around town / cold engine due to closed loop fuel injection.
mpg per bhp has increased significantly IMHO, but has been offset by car weight and emissions as already discussed.
edit : my 1600 Cavalier Mk2s never managed more than 35 ish even on a run.
Last edited by: spamcan61 on Fri 19 Mar 10 at 09:50
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>>mpg per bhp has increased significantly IMHO
per bhp that you don't use, maybe?
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Well some of that bhp goes on shifting 50% ( guess) extra weight, but it is fair to say the Vectra sees a lot less revs than the Cavalier mk2s used to.
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You have it more or less right Espada. Even down to the cars ! I think about 28 mpg was normal back in the day and about 40 mpg now but as you say petrol v diesel.
Of course "average" speeds were ( much ) higher then........cough....
:-)
Last edited by: Humph D'bout on Fri 19 Mar 10 at 18:35
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From 1970 to 1993 my wife and I drove Minis and Fiestas around town. We were lucky to see 35mpg - and most times it was 30mpg...
Son's 1.0 Yaris averages over 40mpg around town.
I drove a Triulmh 2,5PI and averaged 27mpg. A 2litre Mondeo would outclass it in every way and average 35mpg plus. Even a Triumph 2000 struggled to get 30mpg overall.
Anyone who thinks an early Cortina averaged 40 mpg has rose tinted glasses and maybe suffers from a poor memory (codephrase for dementia:-)
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Yes, out of all recognition. That said, there are still lots of thirsty cars on the road. I've got one.
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American thirst to go with the faux American looks?
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My 90bhp, 0-60 in 13+ secs, 1250kg 1972 Triumph 2000 averaged 22mpg mixed driving.
My 167bhp, 0-60 in 8.3 secs, 1300kg 2000 Honda Civic VTi averaged 32mpg overall
My 260bhp, 0-60 in 5.3 secs, 1450kg 2008 4WD Forester 2.5 Turbo averages 26mpg mixed.
Multipoint EFi > Carburretors.
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Not faux Zero alas, the real thing, just retro design job and not bad at that, but it's a Neon under the skin I think. a modern American smallish car. It isn't a guzzler but there are probably several European petrol 2 litre engines that are sweeter and more frugal.
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For the record, I've been doing a lot of miles in the Cruiser and am getting to know it. The cabin, seats, toys, heating, controls and so on are all nice. It's a pleasant place to be, the sound system is all right.
As a drive it isn't so good. It has two modes, relaxed and strained. The engine is lumpish and noisy in many power bands. Power delivery itself is cammy, with a surge between 3,000 rpm and 5,000 or so, but with a certain raucousness that says: I am drinking fuel. Nevertheless if hammered like that it can pick up its skirts and run, keep up with the home counties mimsocracy.
When not pressed I am quite an economical driver. I like low revs and light throttle. Nevertheless in this part of the country one often has to sacrifice economy for progress, for shaking off annoying other traffic and so on. With quite a lot of London and lots of running up and down it's been doing about 28 mpg. Not great but not terrible it seems to me. I have high hopes that on French A roads it would do low to middle thirties.
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The lancer has a very smooth engine (balancer shafts I believe) tho it sounds strained at 4k and beyond. Cruises at 70mph (the speedo is fairly accurate) fairly silently at 3.3k revs.
Its doing 39mpg on half a tank of Motorway, half a tank of urban. Problem is it has a pathetically small tank at 50 litres, and an over enthusastic low fuel warning light means I have never got more than 41 litres in the tank and 360 miles out.
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Engines are more efficient but placed in heavier bodies. I suspect that dropping the latest small diesel unit into a 1980's supermini would get you close to the 100 mpg mark on a steady run.
The progress in efficient engines has been completely cancelled out by weight gains. Sort the weight and economy will reach new levels.
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My local mechanic has just finished putting a 1.7 litre Ford Puma engine in a Mk1 escort body, I'll ask him what economy he gets.
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why bother though?
surely a sorted kent or pinto could give a puma 1700 dink a run for its money?
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Imagine what economy and real world performance if you could drop the VW 1.4TSi engine in a Golf Mk 1!
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i ran a mk1 golf with the 1100 economy engine with the e for overdrive, it was exceptionally economical with its carb,i really dont think in real world driving today it would be bettered?
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I was thinking economy and performance I guess. But the weight of modern cars needs to be reduced. But not at the expense of safety.
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as more cars are on the road safety becomes more paramount
in the old days with the static belts you didnt think of safety as much because you knew if you made an error big time you would die
nowadays its too many other drivers that cant drive thats the problem
l might have said before but i dont enjoy driving anymore purely because its all defensive driving so i dont end up in a box
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My 2003 Passat TDI cost me £2600 about a year ago. Since then I've done just under 20,000 miles having gone from a 2001 Honda Accord which I sold for £2200.
The Passat will get in the region of 60mpg if driven carefully; the Accord could do 30 at best.
Accord fuel cost over 20,000 miles @ £1/litre: £3030.
Passat fuel cost over 20,000 miles @ £1.05/litre: £1500.
Even at 5000 miles per year the cost saving is still there. Engine has been faultless and is much more pleasant to drive than the Accord. I don't think you could lose money buying an older VAG diesel.
Just had a small heart attack as well when I realised how much I've spent on fuel over the last year...
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Manufacturers such as Mercedes and BMW offer vehicles that are far heavier, more advanced and better equipped than the mainstream run of the mill companies, yet their engines on a like for like basis produce far superior economy.
I used to regularly drive an S-Class 320 diesel that, for instance, returned an average of just short of 40mpg and that, compared to a medium sized hatchback with, for example, a 1.9 diesel engine, is vastly superior in terms of overall efficiency.
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Has fuel economy really improved - Pat
