60mpg, is it possible?

Probably due to the BSFC? Rare though! What sort of revs are those two speeds? Is it an auto?

I can probably find a BSFC plot of the Dw12 somewhere here for some idea. Of course 70mph has the advantage over 56mph that if you do take a slight hit in burning more fuel per hour you can see a gain in MPG as you cover more miles in the same time.

I mine for example if Im going about 65mph (outside 100mpg zone) I may aswell do 90 it doesnt really seem to drop much from staying around 70-75mph
 
IIRC most engines are most efficient at the point of peak torque, and a study in the states in the 1950s concluded automobiles were most efficent at 55mph, but that's obviously old as hell! Seems to hold quite well in most cars though.
 
taximike said:
IIRC most engines are most efficient at the point of peak torque.
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Peak torque of full throttle may well be the most efficient full throttle load site but for maintain cruise at part throttle it is not the case.

A BSFC isograph will show you rpm against load (usually manifold pressure) and tell you how many grams of fuel you need to burn to creat 1 KW of power for one hour.

Ie 225 g/KWh. My Focus Zetec 1.8 for example is 288g at a typical load site, yet the 2.0 is 287g! The new Prius 1.8 lowered BSFC over its old 1.5L to a peak of just 210g.

Its all about those charts really, and the shape of the car just defines how many kW you need to generate to hold that speed. Hence defines your burn rate and MPG
 
A lot depends on how you drive though.
My current journey to work in a 2.0 clio yields 34mpg (have tested taking it easy and achieved 40mpg)
the very same journey in a 05 golf TDI (no idea of bhp) driven by my mates GF achieved her 75mpg (i reckon in the same car I would have perhaps achieved 55mpg)
 
Easily.



Thats the economy I am currently getting daily commuting from Leamington to Birmingham! Including the stop/start traffic at each end. At 75-80mph I usually get 62mpg, but this creeps up when the traffic builds up or the variable limits on the M42 switch on.

Over 70mpg soon ticks up if you have the patience to sit at 56mph.

Audi A3 with the 140PS 2.0TDi engine. It's not frustratingly slow either which was a nice surprise.
 
Micra will do 60mpg on flat surface at motorway speeds. Its hard to get it under 50 average. Diesels are probably the best bet for a large car but I never see the point of a small car and diesel


Over 70mpg soon ticks up if you have the patience to sit at 56mph.

Audi A3 with the 140PS 2.0TDi engine.
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This is impressive, have you confirmed its that high manually. ie. you fill it up either end of a 210 mile journey and its only used 3 gallons or close to it
 
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I see average of about 56-57 out the exeo with the 143PS VW lump and have seen over 60 on some of the longer motorway journeys. Thats over 700 from a tank of fuel.

The 1.6 HDI 407 will not get anywhere near those figures and its the most horrible nasty combination of engine and car I've ever had, its slow, noisy, gutless and not that efficient and I had it for 2 1/2 years as a company car.
 
I get avg 57-58mpg on a regular basis when i do motorway runs in my 06 320D SE remapped to 200. I've avg'ed 65mpg once at 2am to Abingdon from Edmonton on the M40 lol. Its really rubbish for town driving though, as low as 29mpg in bad traffic. Most i've ever gotten from a full tank to almost empty was 806 miles according to the trip calc.
 
Jonnycoupe said:
Probably due to the BSFC? Rare though! What sort of revs are those two speeds? Is it an auto?

I can probably find a BSFC plot of the Dw12 somewhere here for some idea. Of course 70mph has the advantage over 56mph that if you do take a slight hit in burning more fuel per hour you can see a gain in MPG as you cover more miles in the same time.

I mine for example if Im going about 65mph (outside 100mpg zone) I may aswell do 90 it doesnt really seem to drop much from staying around 70-75mph
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http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

Ok I'm sort of with you now. It's a manual and in 6th it's 1500rpm at wagon speed and just under 2k (1900?) for 70. I guess I can live with slightly less economy at 70 but actually getting where ever faster :p
 
207 HDi 112 is relatively recent too (with respects to price) but despite me driving it like an idiot for 40% of the time, and cruising at motorway speeds the other 60% of the time, it still did over 60mpg (clocking 62mpg tank to tank).

Nice engine too, rest of the car is adequate enough if you can get over the styling. Still, that's gonna cost you like £12k, lot of petrol money there....Crap pedal layout though.

Nicer car to drive than the Polo BlueMotion too. Something not quite right about that Polo. Good cruiser though and very well built.
 
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Dangerous said:
mpgs.jpg



That was over a trip that was 200 miles long, car 1.9 TDi Skoda
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I'd say yes
 
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