Petrol Consumption

Oct 31, 2005 15 Replies

My old 1993 416 Auto 16v. There 35500 on the clock and drives ok as far as I can tell.



How many mpg should I be getting were I'm 9 times out of 10 making short runs (couple of miles) to work and back?



I filled the tank a couple weeks ago and its nearly 3/4 empty and I've done less than



150 miles. That seems very bad to me.

What could be causing such high consumption?



Thanks for your advice.



Arthur


That depends on the size of the tank.

Short journeys + auto gearbox.

The above, combined with what may turn out to be a small tank would explain it.

I certainly wouldn't expect more than 25mpg on average if you're doing short runs in an auto.

They're a piss poor tank. Used to only get 300 miles out of my 420, averaging 36MPG.

So you're looking at about 200 miles on a 1.6 sluchbox doing short runs on "choke" , running cold where fuel economy is at its worst...about

20MPG.

And the problem is?

The message from "Arthur" contains these words:

If your journeys are that short you'd be lucky to get into the low twenties mpg, possibly even down to the mid teens.

Petrol engines, automatic gearboxes and short jounrneys do not mix.

Actually - internal cmobustion engines and short journeys don't mix. It may not be possible in your case, but if it is, I'd suggest a bicycle or a bus.

I assume you've checked your fuel tank/filter/lines for leaks?

My 99 Golf 1.6 auto gets ~36mpg but that's averaging 7 mile journeys so its warmed up. Its not great mpg on the motorway as it doesn't have a 5th gear.

To get an 'accurate' average mpg (as accurate as the petrol pump), fill her up til the pump clicks off and then reset the trip. Next time fill up again to the click and note how many litres you've put in and how many miles you've done. Divide miles by litres and then multiply by 4.54 to get mpg.

Obviously its best to use the same pump if possible and use most of your tank for accuracy.

Z

I would follow the above instruction as to how to measure the fuel consumption and then repost the query with the full information.

Do use most of a tank though and record what sort of driving you are doing. If you can do it twice (once for town and once for a run) all the better.

We cannot commment on a consumption until we know what it is.

Alan

150 miles to a quarter of a tank is pretty s*it for one of these cars. They have a tank that is a shade less than 10 gallons, so he'll have used at least 6 by the time the gauge hits a quarter. 25mpg even for an auto in town is crap when it's only a 1.6

I'd say it's good for short journeys. Fuel consumption before the engine warms up is extremely heavy.

They regularly do 600 miles to a tank?

So they average just under 60mpg?

Aaahhhhhh, right, I got ya.

Slightly, but if it's all short 2 mile journeys from cold, then it's not going to be much better than that.

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Assuming a tank size of 50 litres, that's 18mpg which is V8 Discovery territory. The short journeys are largely to blame (the car never warms up and is always on its rich mixture "cold start" cycle - like an older car being on the choke), but to check it out fill it to the brim before a long journey and refill immediately afterwards. Then you can work out the miles per gallon properly. If it's less than 30mpg on a long run, something is probably wrong.

Incidentally, the short journeys will drastically reduce the engine and catalyst's life expectancy and are far more polluting than normal driving. The cat can't completely clean up a rich mixture and gets hotter than normal.

I used to get a joyful 13 Mpg out of my auto petrol car when used cold and just a few miles , improved to about 22 mpg when warmed up on a longer journey. steve the grease

You sure? Remember it's not even getting warm.

The official urban cycle figure for a manual 416 was 29 mpg. My diesel manual did about 425 miles on a full tank, which equates to about 45mpg, about right for the combined cycle on these. So if we say 310 to get down to 1/4 tank, the OP is getting about half this, ie under 25mpg. That's probably not too far out for an auto in town driving; I wish our Previa got anywhere near that!

Chris wrote: The official urban cycle figure for a manual 416 was 29 mpg. My diesel manual did about 425 miles on a full tank, which equates to about

45mpg, about right for the combined cycle on these. So if we say 310 to get down to 1/4 tank, the OP is getting about half this, ie under 25mpg. That's probably not too far out for an auto in town driving; I wish our

Previa got anywhere near that!

---------------------- I dunno, our 1.6 Megane auto used to give 35mpg round town, 45mpg on long runs. Our current 1.8 Almera auto gives about 30mpg round town, 40mpg on long runs. Modern automatic gearboxes are a great deal more efficient and pleasanter to drive with than some of the old slushmatic jobs (and the Almera's box is a lot more responsive than the Megane one, too)

[...]

If I only had a couple of miles to work, I would consider other means of transport, possibly involving loosing a bit of my arse at the same time...

If I had only a couple of miles to work, I'd do that, and I'd take the long way in :-)

cheers, clive

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