Fuel Consumption Error

[steeve]

Hi all,

 

Wondering if any if you may be able to shed some light on this before I take my roomster to the garage:

 

Car seems to be running fine, but going through diesel at an alarming rate. Estimated miles to refill does not change when I do not drive the car for a week or so, which (I think) rules out a leak) but if I go for a 20 mile drive, the estimated miles to refill will go down 40 etc. I'm not driving like a maniac and I'm worried that excess fuel is being wasted somehow.

 

Any ideas?

[Ootohere]

Welcome.

 

How long have you had the car and what sort of miles per litre or km per litre did you get, and what do you get now?

So is it actually using lots of fuel or is it just the dash making it look like it does.   You buy fuel as you need not by estimates from doing cold starts.

If you fill the tank and drive a distance and fill again is it a real gas guzzler?

 

 

[Ootohere]

@steeve

This will have a lot to do with your fuel consumption.  

http://briskoda.net/forums/topic/476321-dpf-warning-light-best-practice

 

?

Has your car had the Emissions fix, which can also affect things?

http://skoda-auto.com/services/recall-actions

 

[steeve]

4 minutes ago, Roottootemblowinootsoot said:

@steeve

This will have a lot to do with your fuel consumption.  

http://briskoda.net/forums/topic/476321-dpf-warning-light-best-practice

 

?

Has your car had the Emissions fix, which can also affect things?

http://skoda-auto.com/services/recall-actions

 

 

DPF warning light has only just come on unfortunately, this issue started some weeks ago. It hasn't had the emissions fix, will check now if it needs it - thanks for providing the link!

[steeve]

11 minutes ago, Roottootemblowinootsoot said:

Welcome.

 

How long have you had the car and what sort of miles per litre or km per litre did you get, and what do you get now?

So is it actually using lots of fuel or is it just the dash making it look like it does.   You buy fuel as you need not by estimates from doing cold starts.

If you fill the tank and drive a distance and fill again is it a real gas guzzler?

 

 

 

Had the car nearly two years, but I drive very little and although it may sound strange I don't know what MPG or L/km I was getting previously (I never worked it out) but the gauge is going down noticeably faster now. Would the best thing to do now be to fill it up and calculate exactly how many miles I do before it gets to near empty? 

[KenONeill]

@steeve - The computer does an estimate, based on flow rate and number of cold starts... If you lift right off, at, say, 60mph you can get an estimated instantaneous consumption of several hundred mpg (or even infinite), when you do a cold start you can see an estimated trip mpg of, say, 20:  After 10 miles that can have risen to more like 50.

 

Best to check the available range mode against the trip mileage, resetting the trip when you fill up.

[SurreyJohn]

On 09/01/2020 at 11:39, steeve said:

 

Had the car nearly two years, but I drive very little and although it may sound strange I don't know what MPG or L/km I was getting previously (I never worked it out) but the gauge is going down noticeably faster now. Would the best thing to do now be to fill it up and calculate exactly how many miles I do before it gets to near empty? 

Lots of cold winter starts, little short journeys.   
Diesels will use loads more fuel in this scenario 

 

I suspect your oil hasn’t circulated well either lately, it takes at least 40 minutes of continuous use for the oil to get to >90c and only then will it fully circulate and unclog some of the engine.  
 

So basically have a day out (at least hours drive away) and it will transform your fuel consumption.

[Gmac983]

@steeve

You mention that your dpf warning light has just come. It may be quite possible that your car has been trying (and failing because of lack of use and repeat short journeys) to do dpf regens itself for quite some time. Now it has thrown on the dpf light. Does the dpf light remain on when you next start the car? Has it gone into limp mode? The car would use more fuel whilst attempting to do regens. 

[eccleshill]

Sounds to me like your car is suffering from acute constipation.  Modern diesels are totally unsuitable for short journeys around town.  They need frequent motorway trips or at the very least a good long A road run at 50+mph.   Take it out and drive it like you rented it for at least 50 miles.  Accelerate hard - foot to the floor,  taking it up to around 4000 rpm on each change.  You need to do this every couple of months or so.

 

As for your fuel range "anomaly", the remaining miles is calculated using the fuel consumption over the previous 20  miles.  So if you take a drive and cover the last 20 miles at 50mpg and you have 10 gallons in your tank your range will show as  500 miles.  If you then drive your next 20 miles in crawling traffic at 40 mpg your range will drop to 380 miles.  The opposite is also true - many times I have set off on a motorway trip after a period of town driving and arrived at my destination 100 miles later with more range in the tank than when I set off!!

Also, don't forget that miles remaining is only displayed to the nearest 5 miles.  So you may drive 100yds and that it just enough to flip it over the next 5 miles.

Edited 16 January, 2020 by eccleshill

[KenONeill]

3 hours ago, eccleshill said:

I have set off on a motorway trip after a period of town driving and arrived at my destination 100 miles later with more range in the tank than when I set off!!

Well put; I've done the same, 26.5 miles trip and the trip computer said I'd used -3l of diesel!!

[eccleshill]

Good example today. Car not used so much over last week or so. Just short shopping trips. Set off with around 3/4 tank showing 410 mile range.

Drove for 20 miles on A road and motorway. Trip now shows average mpg for trip was 62.5 and remaining range now 475 miles. Fuel gauge hardly moved.

[KenONeill]

On 17/01/2020 at 12:38, eccleshill said:

Fuel gauge hardly moved

20/410 ~ 0.05, so about 1mm on the needle travel anyway...

[steeve]

Thanks for all your replies.

 

I filled her up over the past month and this is what I got, with a few journeys over 1 hour, the rest just short trips.

 

50 litres: 906km. So about 5.5 litres per 100km, which is pretty average as far as I can tell on sites like these: https://car-emissions.com/cars/model/SKODA/Roomster

 

So nothing to worry about! Thanks for preventing me taking it to the garage!