MPG... What's the problem?

I've literally just got home from a 300 mile round trip... All today... 90% motorway... 28mpg...
Which I think for motorway cruising is very poor indeed.

'something else which ive forgotton'
... your engine spec ?

One hopes that is the SI4 or RacingSnake was doing 90-100mph the whole way!

(02-01-2013 10:18am)PhilSkill Wrote:  One hopes that is the SI4 or RacingSnake was doing 90-100mph the whole way!

I wish they'd do away with the stupid system of reporting fuel economy that they use now, which encourages manufacturers to tune engines to the testing criteria to look good in brochures rather than real-world economy.

I think the standard way should be to use a simple graph showing mpg (or l/100km) at different speeds, which would be achieved on a rolling road in a wind tunnel in a set of standardized conditions, for example:

Speed---Fuel Consumption
10mph 15mpg ***************
20mph 28mpg ****************************
30mph 38mpg **************************************
40mph 45mpg *********************************************
50mph 50mpg **************************************************
60mph 45mpg *********************************************
70mph 40mpg ****************************************
80mph 32mpg ********************************

I know different real world factors would still come into play (hills, a/c, weather etc) but at least it would give you a better idea across the board.

(02-01-2013 01:42am)gw76 Wrote:  'something else which ive forgotton'
... your engine spec ?

LOL
It's an SD4... and not quite 90-100
maybe 70 +/- 10mph.

Not a bad idea, this is my estimation of my SD4

Speed---Fuel Consumption
10mph 15mpg ***************
20mph 28mpg ****************************
30mph 38mpg **************************************
40mph 42mpg ********************************************
50mph 43mpg *********************************************
60mph 38mpg *******************************************
70mph 35mpg ****************************************
80mph 30mpg ********************************

(02-01-2013 01:29pm)RacingSnake Wrote:  LOL
It's an SD4... and not quite 90-100
maybe 70 +/- 10mph.

I'm not being funny, but try doing the same journey at 70mph, I bet your average speed will stay just about the same and your fuel economy will increase markedly. My regular trek takes about 3 hours at 70mph once I'm on the motorways; driving 'faster' doesn't seem to save any time at all (OK, perhaps 5-10mins over 175 miles) as at 70mph you can just plod along in an empty Lane 1, while faster in Lane 2 and 3 you're always having to adjust to other traffic. OK, maybe it's not quite as stimulating, but I guess that's the price you pay!

I may not drive like the Dukes of Hazzard, but I'm certainly no Driving Miss Daisy either, and my expectations are to hit at least 35mpg for anything over 10 miles or so.

at the moment £75 to brim

Night fox, you raise a good point. I regularly drive from Central Scotland to London or Southampton. Driving with the cruise control sat at 70mph once south of Killington Lake services I am often all alone in the inside lane for miles and miles, cruising along never having to touch the brakes yet there are folks in the middle and outside lanes travelling well in excess of the speed limit, all bunched up and standing on the brakes every so often and often I find in the inside lane I am actually going faster than the traffic in the outside land middle lanes. Now if only we could remove the need to use lorries and send their cargoes by canal and ban caravaners from being on the road when I want to travel (although it amazes me how many of them also overtake when I'm doing 70!!) ........... I would never have to slow down to move into either of the "overtaking" lanes! Amazes me also how many Priuses you see travelling at warp speed, they can't half shift when pushed a bit! Alway love it when I come up behind an exotic type car in the inside lane, they are wealthy enough to own one but hate filling it with fuel so sit at 65-70 while all the mundane rep mobiles rush passed!