70mph vs 80mph Fuel consumption test
 

I do several long distance journeys through out the year and as its always the over the same stretch of road and the same distance it provides a useful opportunity to try out different theories. My latest one was to find out if a constant 80mph really did increase fuel consumption by "up to 25%" compared to driving at 70mph as has been stated numerous times.

Each time the distance was over 241miles.

At 70mph I use 31.5 litres averaging 34.5mpg.
At 80mph I used 35.5 litres averaging 30.7mpg

This worked out at an additional cost of £5.07 and 12% increase in consumption.

Is it worth it £5? That is very much a personal decision but all I can say is that I would never advocate breaking the speed limit in the UK and it is very tedious driving at 70mph on a French motorways ;)

Driving what outta interest

Hawkeye R sport. 160bhp standard naturally aspirated although dealer remapped as part of an optional recall, estimated to increase by 5bhp by IM, 23,000miles. Always fed on 95 shell.

A couple of years ago I drove the WR1 off boost for a week just to see what mpg it would do. Used a tankful mainly M25. It averaged 29mpg this was at 65mph in the slow lane, awful. So don't bother now just get in the fast lane 22ish mpg. Would a remap with a switchable economy map be beneficial? Anyone done it?

That seems quite low for driving off boost. That is the one (and becoming an increasingly important) benefit of driving a N/A Impreza in this day and age , the fuel economy is better.

I did very similar with similar results with a hawkeye mapped to 333 bhp

i personally dont bother worrying about how much fuel mine uses as i know that cars like this are not designed to be economical but fun instead, i just drive it and enjoy it like i am supposed to and when it needs a drink i just fill it up again and just keep driving! if i wanted a car with good mpg i most certainly wouldnt have bought a scooby but then it would be boring.

i did a similar test a few years back when i had a company car (1.7TD astra saloon)
made easier by the fact that it had an on board computer that worked out the mpg.

i made 65mpg by sticking to 70mph (Where normal driving would have got me about 53mpg) and thinking way ahead all the time so i never had to use the brakes unless absolutely necesairy and was gentle with my accelleration.

i came to the conclusion that yes, you could save a fair bit of money if you was doing a high anual milage, but, its so tiring and hard to drive like that so it wasnt worth it IMO

i managed 27mpg in a fairly conservative drive to cornwall in my Hawkeye sti
wasnt really tryin for a mpg run, just wanted to make sure i could get to my sceduled stop at Taunton services :D

My STI Wagon 320bhp does 30mpg at 80mph just keep off boost,just keep off the loud pedal,would I change it for economy the hell I would.If I need 48mpg I take my turbo Escort but then if get stuck behind a muppet not a lot you can do but wait!

Well said, my thoughts exactly :luxhello:

I bought mine when I lived in Spain and petrol was the equivalent of 60p per litre. It is my only car and am not in the fortunate position to throw caution to the wind when it comes to the cost of filling it up anymore. I really dont want to sell it as it is a brilliant car so information like this is now becoming a genuine interest, a bit of sense and helpful knowledge passed around on forums such as these means I/we can still enjoy the cars we love. Its nice knowing that you personally dont need to worry about it, thanks.

this fella deffo talks my language!!!:luxhello::luxhello::luxhello::cool::co ol::cool:

+ another 1

Even my economical cars are not economical LOL




:)

My second car is a 4.0 straight 6 petrol Grand Cherokee. That's almost as bad as my impreza on fuel. 17 to the gallon if you drive steady.
I've never been concerned on how much fuel my cars use.
I have the impreza because it puts a massive smile on my face, yes it's expensive to run, but who cares. It makes me happy every time I'm in it.
And my truck, yea that is very juicy, but I know that when my wife and small child are in it they are as safe as possible. You can't put a price on that.

Your only here once guys, fill your cars up and drive them like they were designed for.

That's my opinion on things anyway...

I also own a series 3 4.2 V12 Jag and a 6.3 V8 Bristol. Both of which go through fuel like you can't believe.
I'm soon going to have to get an account at my local BP,, lol.

:confused: 4.2s were straight six or latterly V8

Well spotted there buddy, my bad. The 5.3 was V12 but the 4.2 and 3.4 cars were all straight 6.
I inherited this one when my father passed away along with the Bristol, 4 old Citroens, 3 modern citroens and a car that none of you would of heard of, an Ogle SX250. One of only two cars built. It is being featured in Octane magazine later this year.

http://i214.photobucket.com/albums/c...nts123/046.jpg

http://i214.photobucket.com/albums/c...nts123/047.jpg

http://i214.photobucket.com/albums/c...nts123/052.jpg

Sorry SRSport for getting off topic..

my best efforts at eco runs have got me 341miles to a tank (60 on A raods /65 on motorway)
While driving briskly most of the time i got 230 , so 100 miles or so extra if your prepaired to drive slow enough to iritate old people.

I drive every 2 weeks to the west coast of wales and back again 2 weeks later (from brighton) , so i regularly look at this cost , the difference can be 60 - 90 quid with present fuel prices.
30 quid for driving slow ? pfft id rather get there 2 hours sooner!