Weird MPG readings

Sporky McGuffin · 06-03-2007, 13:18

I went from Guildford to Bury St Edmonds yesterday; about 125 miles each way. I drove similarly in each direction and the traffic was about the same.

Yet on the way there I got 57mpg, and on the way back I got 49mpg.

This morning on the way to work I was back up to 55mpg, so it's not something borked on the car.

Any ideas how I could get such different figures? As I say, traffic was about the same each way, and I was driving at the same sort of speed. Maybe it's all downhill on the way there.

Chrispy · 06-03-2007, 13:21

Air temp I find has a lot to do with MPG. It's better in warmer air but the car feels slightly flatter due to it being less dense.

Also, could be a subtle incline on the way back...the throttle may need to my sliiiiiightly more depressed to keep the same speed.

fletch555 · 06-03-2007, 13:21

Could be slightly downhill/uphill/windy in one direction....???

Sporky McGuffin · 06-03-2007, 16:04

I think it was marginally warmer on the way back. The weather was about the same too; no aircon either way (I gather that uses a bit more fuel). Lights on the way back, but I can't see them making that much difference?

I think a general up/downhill thing is most likely, as you've both said. Still struck me as strange!

MJallday · 06-03-2007, 16:06

Quote:

Originally Posted by Sporky McGuffin

I think it was marginally warmer on the way back. The weather was about the same too; no aircon either way (I gather that uses a bit more fuel). Lights on the way back, but I can't see them making that much difference?

I think a general up/downhill thing is most likely, as you've both said. Still struck me as strange!

when you were in bury... did you do much town driving? the a14 is a great road... bury town centre is a bit, well, naff to drive in... (lived there for 16 years!)

Sporky McGuffin · 06-03-2007, 16:47

Not much, no - drove in, went to a school, did a videoconferencing demo and came home. Bit of a waste of 6 hours and £20 of diesel!

MJallday · 06-03-2007, 17:05

Quote:

Originally Posted by Sporky McGuffin

Not much, no - drove in, went to a school, did a videoconferencing demo and came home. Bit of a waste of 6 hours and £20 of diesel!

lol - which school ?

**mannyo** · 06-03-2007, 17:10

The wind also plays a big part. I drove to Tiverton the other week, got 46MPG there as I was driving into a headwind and 57MPG back.

Sporky McGuffin · 06-03-2007, 17:15

I think it was windier on the way there. Though that was crosswind, whereas I suppose I'd not have noticed a headwind.

The school was St somethings-or-other. Began with a B. Catholic place. I'd forgotten what schools smell like.

MJallday · 06-03-2007, 17:17

Quote:

Originally Posted by Sporky McGuffin

I think it was windier on the way there. Though that was crosswind, whereas I suppose I'd not have noticed a headwind.

The school was St somethings-or-other. Began with a B. Catholic place. I'd forgotten what schools smell like.

St benedicts.... grove park road

-

i went to the one over the road!

Sporky McGuffin · 06-03-2007, 17:21

That's the one!

It was a bit overkill really. One engineer from Bristol (400+ miles), me from Guildford (250 miles) and the sales manager from somewhere around Richmond (200 miles).

So something approaching 900 miles travelling in total. What a waste. Still, I get £100 in petrol money for it.

miho · 06-03-2007, 18:16

Quote:

Originally Posted by Sporky McGuffin

I went from Guildford to Bury St Edmonds yesterday; about 125 miles each way. I drove similarly in each direction and the traffic was about the same.

Yet on the way there I got 57mpg, and on the way back I got 49mpg.

This morning on the way to work I was back up to 55mpg, so it's not something borked on the car.

Any ideas how I could get such different figures? As I say, traffic was about the same each way, and I was driving at the same sort of speed. Maybe it's all downhill on the way there.

Very likely was the wind. Drag and hence the required force to sustain speed goes up with the square of velocity (velocity for that matter is your speed on the road + the speed of the wind). Just a slight headwind drives up your fuel consumtion as if you'd be driving a lot faster. And there you wouldn't be surprised about low MPG readings.

I regularly get that effect between Cambridge and Norwich where westerly winds prevail.

Michael

Sporky McGuffin · 06-03-2007, 20:28

That does all make sense. After all, I'd normally expect about 53mpg - 57 is doing very well in my experience.

ric04vrs · 06-03-2007, 23:24

Quote:

Originally Posted by Sporky McGuffin

Still, I get £100 in petrol money for it.

just don't put petrol in

chris22 · 07-03-2007, 00:29

I always get the same, 50MPG on my wat to work (about 50 miles!) and 55MPG on the way home.

Sporky McGuffin · 07-03-2007, 00:35

Quote:

Originally Posted by ric04vrs

just don't put petrol in

But petrol cars are faster!

06-03-2007, 13:18	#1
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Weird MPG readings I went from Guildford to Bury St Edmonds yesterday; about 125 miles each way. I drove similarly in each direction and the traffic was about the same. Yet on the way there I got 57mpg, and on the way back I got 49mpg. This morning on the way to work I was back up to 55mpg, so it's not something borked on the car. Any ideas how I could get such different figures? As I say, traffic was about the same each way, and I was driving at the same sort of speed. Maybe it's all downhill on the way there.

06-03-2007, 13:21	#2
Chrispy Briskodian Join Date: Sep 2006 Location: Normanton, West Yorks Posts: 1,766 Members Car: 2004 Fabia vRS Thanks: 38 Thanked 68 Times in 57 Posts	Re: Weird MPG readings Air temp I find has a lot to do with MPG. It's better in warmer air but the car feels slightly flatter due to it being less dense. Also, could be a subtle incline on the way back...the throttle may need to my sliiiiiightly more depressed to keep the same speed. __________________ Silver '04 Fabia vRS. Jabba Custom Remap, Seat Surgeons Leather interior, Whiteline RARB, Cupra Console Bushes

06-03-2007, 13:21	#3
fletch555 Briskodian Join Date: Jul 2006 Posts: 550 Members Car: '04 Red Fabia vRS Thanks: 24 Thanked 24 Times in 23 Posts	Re: Weird MPG readings Could be slightly downhill/uphill/windy in one direction....??? __________________

06-03-2007, 16:04	#4
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Re: Weird MPG readings I think it was marginally warmer on the way back. The weather was about the same too; no aircon either way (I gather that uses a bit more fuel). Lights on the way back, but I can't see them making that much difference? I think a general up/downhill thing is most likely, as you've both said. Still struck me as strange!

06-03-2007, 16:47	#6
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Re: Weird MPG readings Not much, no - drove in, went to a school, did a videoconferencing demo and came home. Bit of a waste of 6 hours and £20 of diesel!

06-03-2007, 17:10	#8
mannyo BRISKODA Staff Join Date: Nov 2002 Location: Stevenage Herts. Posts: 11,627 Members Car: Octavia 2.0 TDi Elegance Thanks: 60 Thanked 393 Times in 362 Posts	Re: Weird MPG readings The wind also plays a big part. I drove to Tiverton the other week, got 46MPG there as I was driving into a headwind and 57MPG back. __________________ Manny 2005 Octavia 2.0TDi Elegance combi my skoda website http://www.octaviars.co.uk Join the briskoda.net folding team click Here for more info

06-03-2007, 17:15	#9
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Re: Weird MPG readings I think it was windier on the way there. Though that was crosswind, whereas I suppose I'd not have noticed a headwind. The school was St somethings-or-other. Began with a B. Catholic place. I'd forgotten what schools smell like.

06-03-2007, 17:21	#11
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Re: Weird MPG readings That's the one! It was a bit overkill really. One engineer from Bristol (400+ miles), me from Guildford (250 miles) and the sales manager from somewhere around Richmond (200 miles). So something approaching 900 miles travelling in total. What a waste. Still, I get £100 in petrol money for it.

06-03-2007, 20:28	#13
Sporky McGuffin Briskodian Join Date: Aug 2005 Location: Surrey Posts: 1,034 Members Car: 1993 Zeppelin R200 Thanks: 4 Thanked 9 Times in 9 Posts	Re: Weird MPG readings That does all make sense. After all, I'd normally expect about 53mpg - 57 is doing very well in my experience.

07-03-2007, 00:29	#15
chris22 Briskodian Join Date: Dec 2006 Location: Swansea Posts: 83 Members Car: Thanks: 1 Thanked 0 Times in 0 Posts	Re: Weird MPG readings I always get the same, 50MPG on my wat to work (about 50 miles!) and 55MPG on the way home.

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