Fuel consumption

I get that towing a caravan with a Xantia (same engine). Have power boosted it by Eastcoast Racing and it still returns 48mpg on a run and 44 on mainly town work. Depends what distances you're driving, sitting in traffic jams or running with gentle throttle. All filters clean and correct oil changed as per book? Dave.

I used to get 40mpg winter 43mpg summer out of mine Town work or motorway didn't make any difference.

ogglet

Are you sure you are doing your sums right? If so, check for binding brakes, fuel leaks etc. That does seem awfully low. A mate of mine has one and claims to do @ 50 mpg on mixed motorway/town driving.

-- Stuart

I have averaged to press 50.4 mph over 17904 miles and I count it hard driving taxi kids to school on contract, 2002 406 estate 90 engine oil change every eight thou, service after two oil changes

Malc

It very much depends on the distance. They are very heavy on fuel for the first couple of miles, so if this is the sort of journey you commonly make, it might explain. Try it on a long run.

Not done any sums - I'm going by the computer readout. (I can guess the response I'm going to get!!)

Neil.

:-) Well, you could always do the brim the tank, zero the trip mileage, fill up the nearly empty tank and DO SOME SUMS !!!!! Just to confirm the computer is correct.

-- Stuart

I find the computer readout fairly useless. What I particularly like, is when I fill up, only about half a mile from home usually, the readout tells me that I can do about 480 miles until the next refuel. A hundred miles later (in one journey) and it tells me that I can now do 520 miles..... I just wish it would carry on like that - the further you travel, the longer it will be until you have to refuel.

Oh, and I do know why, before 25 people explain.

What it does show is that if you continually only do short journeys, then you will use a lot of fuel.

On Wed, 25 Jan 2006 19:48:45 GMT, a particular chimpanzee named Neil randomly hit the keyboard and produced:

Round about the same from my 307 2.0HDi (110bhp) on stop-start commuting into and site visits around Manchester.

Yes, it's a Peugeot.

I was once picked up in one of those which was used as a taxi. I got into discussing fuel consumption with the driver, comparing it with my

407 (the driver was thinking of replacing his car with a 407). He was getting a pretty steady 47mpg, but as an airport taxi it was mostly used on motorways. I did notice that he drove at a steady 70mph all the time though.

But I think the 407 9which I have with the 136bhp version is much the same. With a cold engine the fuel consumption is very high, so with a lot of short journeys it does badly. But if I drive at a steady 50mph in 6th gear, I can get spectacularly good mileage. I once saw 117mpg over 4 miles through motorway roadworks (but it was slightly downhill most of the way). 30MPG would be more typical with short journeys around town.

Martin

But diesel engine economy isn't affected by engine temperature - unlike petrol engines, they don't use more fuel when cold.

Well, that certainly isn't my experience. It's true that I don't suffer the loss of power with a cold engine that happens with petrol engines, but when you think about it, the energy to heat up the engine block, oil and coolant to working temperature must come from burning fuel, even with a diesel.

I would also suggest that diesel engines take longer to fully warm up, but they drive just a well when cold.

Martin

But if this is waste heat that won't matter.

On many diesels there's simply more to heat up - heavier block, bigger engine for the size of car, etc.

The reason a diesel takes longer to warm up is that they are are much more efficient than petrol and therefore less fuel burnt means less thermo dynamic heat being produced. Petrol in a cold engine is at a much higher ratio than when its at normal running temperature therefore more fuel in more heat out... simple physics really

Rob J

Rob J

*** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from ***

Well, that's how it is :)

I imagine that your journeys with a cold engine, are fairly short stop-start trips through town or whatever. It's this continuous accelerating and braking that ruins your economy - if you took your car for a trip up the motorway, you'd find it consumed almost exactly the same amount of fuel whether the engine was hot or cold.

Ah, but that exact same heat is still being produced once your engine is warm ! The "heating power" is always being used - it doesn't just cease once the engine is warm :)

That's because they're more efficient than Petrol engines.