How's your Diesel performing?

gebbel said:
Does the extra bhp/ weight of the Audi (if that is the case) over the Saab not result in the lesser fuel economy?
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The Saab is a big heavy car it is bigger then my old Audi A4 would say there would not be much in the weight difference.
 
What is the relationship between BHP and fuel consumption ?

Is it a case that for any given engine capacity i.e. a VW 2.0litre turbo diesel, the higher the BHP, the worse the fuel consumption ?
 
All things being equal, then mpre bhp = less mpg but that is rarely the case

A 200bhp car may give you 35mpg if driven smoothly/sensibly whereas a 100bhp car might only return 25 bhp if you drive it like you stole it.

Also, a 200bhp car in a small bodyshell is gonna be better than a 100 bhp car in a big bodyshell.
(ie, a 520 will give less mpg than a 320 if driven the same, because it has more weight to pull around, even though it's the same engine.)
 
A 1.6 (130bhp) Honda I had returned better MPG than a 1.1 Ford and 1.0 Nissan. I assume thats because you needed to rev the smaller engines harder (depending on the journey) thus negating any fuel economy benefits. Overall running costs with far higher insurance of the Honda made the better fuel economy meaningless though. ditto servicing and repairs. You need to look at the total cost of running/ownership.
 
I started using some of the various fuel saving tips out there for my 2.2 ltr diesel 4WD. I must say I have seen a huge improvement on mileage. I do the same commute daily mostly on a bypass with little traffic. I use coasting, but only on 1 or two hills in a straight line - in the slow lane. I would agree it probably doesnt make a huge difference, but it isnt causing any harm. The main thing ive tried is to not use the speedometer and drive mostly with the tachometer. I keep the engine under 2500 revs at all times, even going up through the gears. When I can I keep it around 2k and sometimes 1500 when theres traffic. Last tank got me 37 miles/gallon. I know that isnt anything compared to a decent fuel efficient car - but I think its a huge improvement on what i was getting.
 
aircobra19 said:
A 1.6 (130bhp) Honda I had returned better MPG than a 1.1 Ford and 1.0 Nissan. I assume thats because you needed to rev the smaller engines harder (depending on the journey) thus negating any fuel economy benefits. Overall running costs with far higher insurance of the Honda made the better fuel economy meaningless though. ditto servicing and repairs. You need to look at the total cost of running/ownership.
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I totally agree. But driving a car with 130ps rather than say 60hp is much less work and safer. Driving a car with very low hp is only good for town runs. If you are happy with it then fine, but I think a car with 100-150 hp is fine,any more and it's just a waste! A1.0 car will be more economical in town than a 2.0tdI for sure.
 
Mad_Lad said:
I totally agree. But driving a car with 130ps rather than say 60hp is much less work and safer. Driving a car with very low hp is only good for town runs. If you are happy with it then fine, but I think a car with 100-150 hp is fine,any more and it's just a waste! A1.0 car will be more economical in town than a 2.0tdI for sure.
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Not always Driving a Honda with peaky power delivery is a pain in traffic. Often a small 1 lt is far easier with a lighter clutch etc. Less effort and its cruises over speed bumps that you can't with a sports suspension. Most city driving is at slow speeds too.
 
aircobra19 said:
Not always Driving a Honda with peaky power delivery is a pain in traffic. Often a small 1 lt is far easier with a lighter clutch etc. Less effort and its cruises over speed bumps that you can't with a sports suspension. Most city driving is at slow speeds too.
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But on the open road the honda would be much better power wise. Of course the 1.0l car will sometimes feel better in town. and the lack of power won't usually matter anyway. Oh boy if we didn't have cars to talk about! lol
 
Mad_Lad said:
But on the open road the honda would be much better power wise. Of course the 1.0l car will sometimes feel better in town. and the lack of power won't usually matter anyway. Oh boy if we didn't have cars to talk about! lol
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Exactly.
 
Thanks to all the tips in this thread, I have managed to increase the fuel efficiency of my 2005 Audi 2.0TDi 140BHP from just under 43MPG (forgive the imperial!) to 47MPG in one week. Changes I made have included:
1. Checked tyre pressures and found them to be too low (all less than 30PSI) so am now running with 34PSI on each tyre.
2. Listened to all the negative advice re "coasting", but have started to carefully use it...with noticeable benefits to fuel consumption.
3. Quicker gear changes i.e not letting the revs go past 2100RPM before changing up.
4. Most importantly....keeping to the legal motorway speed limit more than before. Less speed = less wind resistance and more fuel saved.

Thanks all
 
I think I read somewhere that generally speaking, once you go over 100kph, fuel consumption increases fairly dramatically in most cars regardless.
 
Caveat said:
I think I read somewhere that generally speaking, once you go over 100kph, fuel consumption increases fairly dramatically in most cars regardless.
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Sorry I can't give the source but I read somewhere recently that 10 mph over the speed limit ( I assmume that means the 100kph limit) uses 10% more fuel!!! (mostly due to the increased wind resistance)
 
Wind resistance / drag increases exponentially as speed rises, so a small increase in speed means even more resistance, which means you engine's got to work harder. This converts to poorer mpg at small increases in speed..
 
aircobra19 said:
A 1.6 (130bhp) Honda I had returned better MPG than a 1.1 Ford and 1.0 Nissan. I assume thats because you needed to rev the smaller engines harder (depending on the journey) thus negating any fuel economy benefits. Overall running costs with far higher insurance of the Honda made the better fuel economy meaningless though. ditto servicing and repairs. You need to look at the total cost of running/ownership.
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And, like a pendulum, it can go the other way, too. my current 14-yr old 3.0 petrol, is getting about 25mpg - but it's depreciated almost completely already, I had enough from selling our 07 Galaxy 1.8Tdci to buy it for cash - so no repayments, and no interest, so it currently represents astonishing value for money. Oh, and cheap to insure, too. (old dinosaur, I guess !!). A new econobox would have to be as cheap as chips, and do a squillion miles to the gallon to match the total cost. Sometimes more is indeed, less...........!!
 
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