I'm new to this Forum, but have had a good look around and can't see anyone else posting about this.....

 

I'm a bit of an MPG nerd and have frequently got 80+ mpg (indicated) out of my Greenline over the past year on my 20 mile commute (max was 90.3!!). This is backed-up by on-going full-to-full calculations giving me around 70MPG average - this includes school runs and my wife driving etc.

 

I'm not looking for yet another debate about possible MPG vs manufacturer's etc.

 

But since coming back off holiday (with the car being parked for 2 weeks) the MPG is noticeably and consistently lower - in all circumstances. I'm struggling to get 70mpg on my commute....

 

Does anyone know what might be causing this?

Did you buy some new shoes on holiday that are a bit heavier?

Worth having it checked for any fault codes.

 

Have you changed fuel? Checked your tyre pressures? Checked that the brakes aren't binding?

 

Gaz

28 minutes ago, CallmeGaz said:

Checked that the brakes aren't binding?

 

Gaz

 

Good shout - parked up for two weeks may have contributed to brakes binding. I'm guessing anyone getting those sort of MPG figures doesn't use the brakes hard (if at all 😊 ) so maybe they need a few harsh stops...?

Cant believe that its 20 years ago but the same thing happened to me the last time I took a proper holiday, I was away a month and my petrol Galaxy was running really sluggish, i was jetlagged so didnt really notiice, if finally ground to a halt with a completely blocked catastrophic convertor, it was running 100% before I left and thrashed to within an inch of its life every day, no idea what happened while it was standing.

 

Perhaps the same thing could happen with a DPF?

8 minutes ago, J.R. said:

 a completely blocked catastrophic convertor,

 

This made me chuckle 😀

I stuggle to get more than 47mpg out of my 1.6 diesel automatic. If I drive a 300 mile motorway journey and stick at 60 (who does that?) I can get 60 out of it. But a standard mix of A roads, motorway and minor roads, I average 47, #ShouldHaveBoughtaPetrol

I would also go with the brake idea especially if was parked outside & expsosed to the weather as its starting to get colder during the night these days leading to condensation.

Also, how long has it been since returning from your holiday…. Maybe wait until you tank again to see if it starts to improve?

and checking your tyre pressures having changed cant hurt.

Edited 11 September, 20196 yr by Gabbo

35 minutes ago, NikTheGeek said:

I stuggle to get more than 47mpg out of my 1.6 diesel automatic. If I drive a 300 mile motorway journey and stick at 60 (who does that?) I can get 60 out of it. But a standard mix of A roads, motorway and minor roads, I average 47, #ShouldHaveBoughtaPetrol

 

That seems low for a 1.6 diesel tbh.

My parents have the old 1.9PD Octvia 110.  They get 60mpg on shorter journeys and 70+ on a decent run.

 

Hell, I drove my wife's 180bhp 2.2 Diesel mazda to work this morning and got 52mpg over the 9 miles, with a heavy right foot.  I've had that over 70mpg on a decent run too, although realistically 58-62 is more easily achievable and repeatable.

You could do a rough test on the brakes for binding, find a empty flat road (!) get to about 30 and drop the clutch, does it coast nicely, or is there quite a lot of drag ?

 

Also visually check the brake disks, are they shiny all across, or do they have film of rust from when you parked up.   How long since your brake fluid was last changed, remember it is hydroscopic (absorbs moisture from air), sitting there during falling temperatures may have led to condensation which has caused poor fluid, or fine surface rust on pads and disks

 

Then on your deserted road, give it some welly in a low gear (get the engine up near the red line for few seconds) then do an emergency stop.  Try this 2 or 3 times and hopefully will clear out any grot and sort it, worst case is wont make any difference.

 

 

1 hour ago, Alex-W said:

 

That seems low for a 1.6 diesel tbh.

My parents have the old 1.9PD Octvia 110.  They get 60mpg on shorter journeys and 70+ on a decent run.

 

Hell, I drove my wife's 180bhp 2.2 Diesel mazda to work this morning and got 52mpg over the 9 miles, with a heavy right foot.  I've had that over 70mpg on a decent run too, although realistically 58-62 is more easily achievable and repeatable.

 

I've probably had the #dieselgate "fix". Does your parents 1.9 have a DPF? I imagine it does. I agree it's low and the claimed mpg of 70ish was why I got the car. But it has 17" wheels rather than 16 which I gather makes a bit of a difference. Enough of a difference to take it from £0 road tax to £20 anyway!

56 minutes ago, NikTheGeek said:

 

I've probably had the #dieselgate "fix". Does your parents 1.9 have a DPF? I imagine it does.

 

Very few of the 1.9s had dpf's if any. 

No, it was way before that, it's a 2001 model.  Which makes me think with 15+ years progress and a smaller capacity, I'd imagine far better figures are possible.

And given, as I say, the wife's mazda is larger capacity again,  180bhp,  with a DPF and the car weighs maybe 150-200kg more and that can get high 50s makes me think that 47mpg for the 1.6 is very low.    

According to "Honest John" 51.6 is the average for my car.

 

https://www.honestjohn.co.uk/realmpg/skoda/octavia-estate-2013/16-tdi-110-dsg

 

So I'm not a million miles out with my roof bars, 17" alloys and fair few B-roads in the mix.

Once you get into the higher MPG range you start to notice factors that effect fuel consumption you didn't before.

Such as wind, rain, tyre pressures, having your lights on, AC, outside temperature, etc.



 

True, my Accord gets about 26mpg whatever I do.  It's low consistently!

 

I maintain though that worrying about mpg has depreciating returns.  When we bought our Mazda I aimed for somewhere in the 40s for day to day and can do over 50 on a run.

 

The difference between 25mpg and 50mpg is significant and relatively easy, it halves your rather high fuel bill.  The difference between 50mpg and 60 mpg is not, it drops your pretty low bill by 16%.  Even if you go from 50mpg to 100mpg and halve it again, unless you do mega miles you're saving 50% of a bill that's just not very high anyway.  

The national average is 10-12k miles a year I think and for that I just don't see the point of trying to be THAT economical.   

 

For me, having a car that does 50mpg on long journeys is useful and means doing 500 miles in a week on a UK camping holiday doesn't cost the earth.  Anything above that and I probably save £100 a year and it's just not worth the effort or power sacrifice.

 

I had a similar problem with my Superb and never quite got to the bottom of it.

 

Symtoms:

Long drive down to a dealership in my 150 TDI, average MPG for that trip was 55.  I then px'd my car and drove home in a 280 TSI and my mpg was 32.  Both cars were Superb 3 Sportlines.  

 

Alex W makes some very good points, I am at the obsessive end of the fuel consumption figures but after years of living on savings its become a habit, the money is no longer a major issue and were I to work out how much I save by not enjoying my drive so much its probably not a lot of money.

 

Re different consumptions on the same journey. OK I know Penguin was speaking aboy different vehicles, I live in a not particularly hilly area but on a regular 30mile journey the outgoing comsumption would be 65mpg and the return at exactly the same speeds would be 50mpg, the overall will be exactly my long term average of 57mpg, my fuel computer has been reset via VCDS to tell the truth, it was 13% overoptimistic.

 

It doesnt matter how many hills there are along the route its the start and finish altitudes that make the difference, if I use my runners watch on the journeys then the graphics show clearly why the consumption is so different.

Edited 12 September, 20196 yr by J.R.

On 10/09/2019 at 20:36, Alex-W said:

Did you buy some new shoes on holiday that are a bit heavier?

 

Thanks all for your comments/suggestions. Several weeks on and it does appear that Alex-W was probably the closest.... I think I had effectively forgotten how to get the v high mpg out of it after 2 weeks of driving a hire car!!

 

Reasonable but slow acceleration. Loads of anticipation. Carrying speed (when safe) through junctions. Windows closed. Good tyre pressures. Right gear. Cruising 50 - 60 mph. etc. etc. etc.

These all help but the real trick is;

Once you get to the speed you want you momentarily lift-off completely and then touch the accelerator as lightly as you can to maintain speed - this changes cruising on the flat from 70-80mpg to 90-100mpg!