Mpg

[wrx kenny]

As we all know the price of fuel is ripping the pish at the moment , I have a 500 mile a week commute or there abouts . Seeing as my bug is my only car I have to take it easy wae the loud pedal so I have been monitoring my fuel consumption the last wee while and driving slower than miss daisy , now this is where I'm confused I've been sitting between 50-55 mph on the motorway and returning about 26-29 mpg , last week I was told to drive slightly faster and that would return better mpg do I did , I have been sitting about 55-63 and my consumption did go ip to between 32-33mpg roughly but definitely an improvement . How can this be when I'm going faster and getting improved mpg , I dont understand this ..... Confused I am

[terzo neil]

it is all done to injector times, sitting at 55mph will be around 5ms, according to onboard monitor display, sitting at 80mph with an injector time of 3.4ms wil use less fuel on light throttle than cruising at 55mph, efficinet band of any engine is around 3000rpm, i can get 37mpg sitting at 80mph with an injector time around 3.5ms and nearly 400miles to 1 tank of fuel

if i sit at 55mph and drop to 4th gear to bring revs up to around 3000 rpm, my injector time drops to around 3.8ms instead of 5.6ms, thus use less fuel

[spect]

blimey. learnt summat new today then, thanks

[scouk]

Neil I'm nominating that as post of the year!!

Way more informative than what I was goign to say.. ANd that was somethign like the general message drivers get is theat 50mph in high gear is the most efficient drivign speed.. When really that's a very vauge guestimate.. It depends on the type of car drag coe-effs and stuff..

But you've gone straight to the heart of it! Nice one! Gonna have to keep a closer eye on that now.. Only gettign 23-24mpg on my scoob at the moment.

Oh and a quick tip for Kenny.. If you have the space for a 2nd car, it may be worth considering one.. It's cheaper for me to run the scoob and another car than it is to just tun the scoob! Mostly down to fuel costs (getting 40-45MPG on 2nd car), but also tyre wear part costs etc. This includes taking into account the extra cost of mot/tax/insurance! I was surprised! I worked out that so long as the car didn't cost me more than £1,000 I'd reclaim that money back in savings after the 1st year! As it happens I got the car for nothing so practically instant saving! That was over two years ago! Downside is no driving the scoob every day, and not quite the luxury of a merc, but means i can speend the money saved on making the scoob a little bit better for the evening/weekends

Edited August 14, 2011 by ScoUK

[davey l wrx]

Unfortunately the Ka cancels out the street cred the scooby gave you though Al

I've been getting a constant 27-29 mpg by only going over 3,500 rpm when i need to. I even got an average of 27mpg on the highland fling! I had to head down to Telford for a course a couple of months ago and got it to just over 30mpg on a steady cruise down the motorway. Alot of it comes down to if your car is standard or modified and your driving style.

[terzo neil]

thanks Al

thats why i now run a merc 208cdi for work with the new company i work for and thats why i have 2 scoobs to play with, as my cars are not daily drivers, and only put fuel in when i need it

classic has a andyf map, done over 1100 miles on 2.75 tanks of fuel going to south of france in it 3 years ago, cruising at 120km/h on french motorways

newage has a prodrive ecu, and can get nearly 400 miles to 1 tank

as for insurance, on my 2 cars on multicare policy and not daily drivers grand total of £587 fully comp on both for a year

Edited August 14, 2011 by Terzo Neil

[scouk]

  On 14/08/2011 at 09:24, davey l wrx said:

Unfortunately the Ka cancels out the street cred the scooby gave you though Al

True... But it's descreet apart from SIDC sticker on back window Also handles quite well for such a poxy little car.

Once the price of 2nd hand diesel foresters drop to an affordable price the ka's getting swapped out

I was getting about 26-27mpg on the scoob before I got the ka so the economy drop is probably more to it being used more of a 'toy' now rather than used everyday and trying to keep to steady driving all the time. Have seen 35mpg on long drives down south so is possible.. Had a couple longish trips on the current tank of fuel so fingers crossed it back up to somethign sensible again. Also just remembered it on VPower at the moment because there was no T99 locally when I needed a fullup

I'm about £750 for insurance on both cars.. But got my 3 points removed this year so shoudl help next time round.

Edited August 14, 2011 by ScoUK

[badbaz]

Thought there was more chance of Elvis posting in here!!

[wrx kenny]

Nah elvis left the building

[ur.a.bus]

  On 14/08/2011 at 13:25, Dipsy said:

Good write up there Terzo Neil .

best i have had is 23mpg, gonna have to see what i can get now

[scouk]

Funny this thread should come up actually.. Was considering buying a ScanGuage-II device for the car, mainly to get a MPG readout, I know... elvis ...... Also saves hassle of lumbering a laptop around the place, just to montior stuff..

Can also display all sort of other useful datapoints as well..

[kennyuk300]

  On 14/08/2011 at 15:29, Dipsy said:

Best i have seen 30mpg when i went to falkirk wheel and mine varys from 26mpg to 28mpg

Alright Kevin ,you got something to show you or just simple calculation ??

[davey l wrx]

I use the Road Trip app on the iPhone. It tracks the fuel economy and what you spend on servicing and other expenses. It's quite handy as it projects the monthly and yearly spend (on servicing, tax, fuel) and expected yearly mileage.

Though it has to be said i have looked at thescan guage before.

[andrew_forrest]

  On 14/08/2011 at 08:20, Terzo Neil said:

it is all done to injector times, sitting at 55mph will be around 5ms, according to onboard monitor display, sitting at 80mph with an injector time of 3.4ms wil use less fuel on light throttle than cruising at 55mph, efficinet band of any engine is around 3000rpm, i can get 37mpg sitting at 80mph with an injector time around 3.5ms and nearly 400miles to 1 tank of fuel

if i sit at 55mph and drop to 4th gear to bring revs up to around 3000 rpm, my injector time drops to around 3.8ms instead of 5.6ms, thus use less fuel

You are missing an important aspect. The higher the rpm, the higher the frequency of injector opening.

For example, 4ms at 3000rpm uses the same fuel as 3ms at 4000rpm.

Andy