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Fuel efficient driving.
Comments
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I've been dicking about trying to improve the MPG on my daily commute. I do 6nights of 60miles.. but usually I have a van for one night so call it 320mile weekly commute... 300 work + 10 to where I shop + fill up and 10 home. Always uses Shell brimmed to the top to the point of dribbling down the Quarter..... And always use same car as its loaded with work gear.
Last 3 weeks fuel useage all on Shell normal Unleaded and using a X20XEV powered Vectra circa 54mile dual carriageway......
Week 1 £68... 380miles this week as no van to use on a Friday night... I cant recall the £ per litre*...
Week 2 £58... 320miles as used the van... I cant recall the £ per litre*
* I should have receipts as I keep them.... I'll update as when I find them
Week 3 week just gone... fuelled up 13/03.. 320 miles 35.20 litres @ £45.72 @ £1.29.9litre... Works out at 41.23mpg brim to brim @ 4.546litres per gallon... Not bad for a 99 X20XEV Vec:D... I'll try the Z18XE powered one in next few weeks.... Then maybe the ML:(
All I've done is plan ahead...No harsh accelaration... No harsh braking.. Bit of coasting sticking at just under 60mph and one reasonably quick blast as it tends to gum up the breathers & ICV... Its due a breather & throttle body etc clean0 -
skiddlydiddly wrote: »Car coming towards you, another car suddenly pulls out in front of you.You can't brake enough to avoid hitting it up the ar** but putting your foot down going an exta 5mph would let you drive around on the other side of the road and still miss the oncoming car.Having to dip the clutch and pick a gear when you have no reference point takes time.
Thats one off the top of my head
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LOL - so you put your foot down and have a crash at 55mph instead of 50mph
Sorry, but the old 'accelerate out trouble' does nothing but get you into trouble faster.
A good, alert driver is still in full control of a car even when coasting.0 -
Harry_Flashman wrote: »What's FPS mate?
Frontal Protection System.0 -
skiddlydiddly wrote: »Well my dad has had someone pull out in front of him before and he hit them as he couldn't slow down enough and they tried to blame him too, so it can happen.
Plus, I already said that in my example(not the best I agree)that there wasn't enough time to brake and that an additional 5mph would have got you past, coasting at the same speed wouldn't.Its fine to disagree with my example but try and keep to the parameters I used.
If someone pulled out in-front of you without enough time to brake you got naff all chance of driving around them you either A) end up in head on with the car from the other way.
smash the driver side of his car then probably have the oncoming vehicle crash into you.
If you were lucky enough to get beside the car that just pulled out in front of you it would now be accelerating away so you've now to accelerate faster than they are good luck with that one you'll need it.0 -
Harry_Flashman wrote: »Heavily dependant on the type of engine.
On all modern engines he right only if your using carbs would be the only time this is not true.0 -
DirectDebacle wrote: »Frontal Protection System.
That is an approved FPS, approved by me to protect my headlights from vehicles, road furniture, pedestrians, cyclists and countryside flora and fauna.
(for those without a sense of humour that's a JOKE BTW)
Anyhoo that's taking the thread completely off topic.0 -
There have been several articles in the motoring press recently recommending max throttle at low revs then changing up at around 1500 in a diesel and 2000rpm for a petrol car. This ties up with wikipedia:tomstickland wrote: »RATE OF ACCELERATION - WHO CARES?
Often when I read articles or comments about fuel efficient driving then people talk about "gentle acceleration". My opinion is that, within reason, rate of acceleration is irrelevant to obtaining good mpg.
"modern diesels being able to reach an efficiency of about 40% in the engine speed range of idle to about 1,800 rpm. Beyond this speed, efficiency begins to decline due to air pumping losses within the engine.would seem to tie up with the fact that most modern diesels achieve a max efficiency of 40% at around"
http://en.wikipedia.org/wiki/Engine_efficiency
I seem to get improved results driving around town doing this.
You will have to prove it to convince me. The kinetic energy put into the vehicle is the same for each example but the engine will be requires to produce twice the force to accelerate in half the time. Your example only works out if the engine efficiency doesn't vary with power output or rpm.tomstickland wrote: »WHY I REALLY DON'T CARE ABOUT ACCELERATION
So why is rate of acceleration unimportant? Because a higher rate of acceleration is balanced out by an equivalently shorter time of acceleration. Twice as much acceleration for half the time - it balances out. If a driver wishes to accelerate from zero to, say, 60mph, then the kinetic energy put into the vehicle is the same regardless of rate of acceleration. Taking 20s to reach 60 with the throttle hardly pressed is no better than 10s with twice as much throttle.
Unfortunately engine efficiency maps are not enough. This link shows fuel economy versus speed for a selection of vehicles tested. http://en.wikipedia.org/wiki/File:Fuel_economy_vs_speed_1997.pngtomstickland wrote: »LOWER CRUISE SPEED WILL SAVE FUEL
If the driver decided to lower their cruising speeds then they could improve their mpg. This effect will work down to quite low speeds. At very low speeds the engine will not be loaded hard enough and its efficiency will fall off. So the most efficient cruise speed is going to be somewhat lower than the 56mph in 4th or 5th that most manufacturers design for - it will possibly by in 2nd or 3rd gear at the optimum engine rpm (somewhere around 2-3K). I've got some engine efficiency maps that will show this.
It shows there is no hard and fast rule which can be applied to all vehicles.
Agreed, no argument theretomstickland wrote: »BRAKING IS BAD
All braking is clearly throwing away energy. It turns the kinetic energy of the moving vehicle into heat. That energy came from the engine in the first place. The total amount of braking done is a measure of how much energy is being wasted.
Agreedtomstickland wrote: »Gradual slowing by coming off the throttle in the cruising gear and then gradually moving down the gears as the rpm falls too low is the method that is being advocated. Most engine management will cut the fuel to the engine under these circumstances.
No coasting with the engine not running gives the best fuel efficiency. I believe hybrids do this safely.tomstickland wrote: »COASTING VERSUS ENGINE BRAKING
Coasting is bad driving practice, so this should not be discussed!
However, from a point of view of the physics of it I suspect that coasting with the engine running would actually give the best fuel efficiency.
In normal cars it is better to run with the engine on in gear and either no throttle or just enough to maintain speed than to coast. I have tried each approach to some long descending dual carriage ways near me and coasting shows a higher fuel consumption.
The AA website has some good advice covering almost everything that has been on this thread so far:
http://www.theaa.com/motoring_advice/fuels-and-environment/drive-smart.html0 -
That is an approved FPS, approved by me to protect my headlights from vehicles, road furniture, pedestrians, cyclists and countryside flora and fauna. (for those without a sense of humour that's a JOKE BTW)
Anyhoo that's taking the thread completely off topic.
Not completely.
The FPS fitted to your vehicle will have altered the aerodynamics and added weight to the detriment of m.p.g.0 -
No coasting with the engine not running gives the best fuel efficiency. I believe hybrids do this safely.
Not really sensible to compare a car designed to automatically switch the engine off and on with a normal vehicle.
Without the engine running I also lose the power steering, brake servo and aircon.0
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