I did think that the 1.4 HDi Citroen C2 and C3 having fuel consumption in the 65mpg region was good. But....
A typical 2.0 TD large hatchback weighs about 50% more
Has an engine 50% bigger
Produces 84% more power (138 v 75bhp)
Accelerates quicker, especially in-gear acceleration
and... only uses about 1/3rd more fuel.
So, where are the 80-100mpg small cars then? Until then I'm over the moon with 45mpg.
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They are there, or at least they were - the Audi A2 and the Seat Arosa/VW Lupo, all with a 1.2TDi engine, skinny tyres and reduced weight. All were designed to travel 100km on 3 litres of diesel, which *I think* works out at about 93mpg.
Problem was noone wanted to buy them on the continent, so they weren´t even imported into the UK. I get the impression it was a bit of a cockup all round for VAG.
Contrast with BMW and their MINI replacement - with priorities of style, handling and performance rather than clever packaging and/or fuel economy, and it sells like the proverbial hot cakes.
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"Produces 84% more power (138 v 75bhp)"
That's the clue. A small car needs more of its available power, and therefore runs at wider throttle openings.
If you ran both engines flat out, you'd see a much bigger difference in consumption! Even 50cc scooters 'only' manage 100mpg or so, because they *are* running flat out.
Running a car with reasonable aerodynamics at a steady 60mph on the level only absorbs 10-15hp. The rest is for hills and acceleration.
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Small diesel / electric hybrid cars must be more than a twinkle in the eye at research and development departments of big manufacturers by now. When these hit the market, to anyone who chooses to fork out the extra purchase cost, 65 mpg will look unremarkable.
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Citroen claimed you would get 100mpg from a C1 diesel if driven carefully. So the Times put it to the test, with surprising results (which you may have seen last year):
snipurl.com/msb4
They drove a C1 diesel round the M25, and also a C1 petrol just as a comparison, and the petrol did better mpg...
IMHO at todays prices diesel is only cost effective if you do high mileage, and if you do high mileage you're better off driving a bigger car for comfort reasons. You wouldnt catch me doing 40k miles per year in a Citroen C1!
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smart CDi will get you in to 80+ mpg territory, no probs.
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Difference in bhp per tone figures between small HDI diesel in C2 and bigger TDI in, Seat Leon for example is actually about 30%...
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A question - do small diesel engines take as long to break in as larger ones? As far as I can tell, my 2.2 Honda engine should inprove it's fuel economy by between 20 and 30% in the next 6-8k miles (from about 40 to 50-55 mpg and based on forum posts and other info on the electrical interweb).
If this is true in smaller engines, then would the diesel not smash the petrol again once run in?
Just a thought...
G
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Gordon, you sure about that? Getting 55 from a 2.2 Honda diesel engine? IIRC there have been a few threads on here complaining about the consumption of Honda diesels?
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No, I'm not sure, but I'm hoping!
There was a lot of fuss on threads more than a year ago about people getting precisely the mpg I'm getting at the moment (40 or thereabouts), but then followups posted saying it had gone up to 50+ after 10k+ miles.
The original thread was:
tinyurl.com/mj5cm
and the update was:
tinyurl.com/m87ay
I hope. If the tinyurl thing works.
Gord.
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A question - do small diesel engines take as long to break in as larger ones? If this is true in smaller engines, then would the diesel not smash the petrol again once run in?
Yes would be interesting to see The Times do a follow up test with cars that have done 15 or 20k miles.
I've seen it written elsewhere that diesels take a lot longer to loosen up than petrols because the average driver is consistently using less revs than in a petrol car. I would assume this would be similar for small and large diesel engines, because the same amount of revs are normally used?
Keep us posted on whether your car gets the economy boost you mention?..
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I recently had the use for ten days of a Renault Modus 1.5dci.Driving it "like a vicar" on my daily commute of dual carriageway and motorway,I acheived 55mpg and no more.My wifes 9 year old 1.4 petrol polo achieves 47mpg on the same route.
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dCi engines need at least 10K on the clock before they loosen up. Mine went from 48mpg to 56mpg and that's in a much bigger and heavier Megane.
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The modus dci i used had 20,000 on the clock.
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Driving like a vicar ( a rare event i know) would get me 56mpg on the Goona
------------------------------
TourVanMan TM < Ex RF >
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Driving like a vicar
I love that phrase, one of my best friends who is a vicar spent some inheruted money on a 6 year old Audi S4, driving like he does would not do much for my fuel consumption.
I think he works on the quote from Convoy
"I don't read anywhere in the good book where it says Thou shalt not put the pedal to the metal"
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My vicar friend has nine points and the way he drives his new Altea 2.0 TDi a ban is on it's way!
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I think he works on the quote from Convoy "I don't read anywhere in the good book where it says Thou shalt not put the pedal to the metal"
LOL! So funny, I accidentally kicked the power connector out of the laptop!
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On Shell Optimax i can get about 53mpg on a good motorway run which i did about a month ago, majority of the way on M40/M6 heading up North, as soon as the neadle was nearing the red after passing Carlisle on the A74 (M) i dropped my speed to about 60 mph until i reached Abington services (another 24 miles), that might of made a small difference although that part of the route was quite hilly at places!
--
Its not what you drive, its how you drive it! :-)
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I used to drive a 2002 registered Mercedes S-Class C320 diesel regularly all over the UK.
Average fuel consumption was 35-38mpg.
I regard that as remarkable for a car of such weight and performance capability (just 0.6 seconds slower on the 0-60mph sprint than the petrol engine).
My own view is that the BMW, Mercedes, Lexus etc luxury cars produce staggering fuel consumption figures for their weight and engine sizes, especially when compared to smaller cars with smaller engines.
Their superior efficiency is quite astonishing based on a like-for-like basis.
- - - - - - - - - - - - - - - - - - - - -
What\'s for you won\'t pass you by
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Just got back from Lake District. Kendal to London on M6/M1, N/Circular, then a weeks worth of local stop start stuff. 70-80mph on the motorway, achieved average of 42mpg in a C4 VTR+ 1.6 diesel. Not what I was expecting really. I think that town driving, light on throttle, will get me less than 40mpg.
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My own view is that the BMW, Mercedes, Lexus etc luxury cars produce staggering fuel consumption figures for their weight and engine sizes, especially when compared to smaller cars with smaller engines. Their superior efficiency is quite astonishing based on a like-for-like basis. - - - - - - - - - - - - - - - - - - - - - What\'s for you won\'t pass you by
>>
I thought the Lexus IS 200 V6 was noted for being thirsty?
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I thought the Lexus IS 200 V6 was noted for being thirsty?
It's actually a straight 6 rather than a Vee. The engine really does like to be rev'd and you need to work it to get the most out of it so they do get a bit thirsty if you drive them hard
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"luxury cars produce staggering fuel consumption figures for their weight and engine sizes"
Apart from small increases in aerodynamic and rolling resistance, it doesn't require any more power to run a big car at a given speed than a small one, so the difference is not so surprising. If you took full advantage of the 0-60 acceleration every time you took off, the fuel consumption would be a lot more noticeable!
A big car driven gently is a good overall solution, IMHO. Cheap to buy, comfortable and durable, and the extra running costs more than offset by the slow depreciation (assuming it had lost most of this when you bought it).
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Last 1000 miles, mostly long distance (Cheshire to Fife and back), 58mpg - 99T 306 HDi.
Agree about minimal cost advantage of fuel though. Should be some in May when we take the car to Ireland.
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To offer Gordon some hope my Accord Tourer has averaged just over 50mpg over 64k in 2 years. Best tank was 55.
Not astounding since the Vectra 2.0 Diesel I had 7 years ago averaged 56mpg over 43k and the best tank was 72!
So why are small cars not doing better!
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Are you sure your maths are ok.
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My mental arithmetic is terrible - that is why I use a spreadsheet, the miles per tank from the trip, and the volume off the receipt.
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