Kinda ridiculous that diesel is so much more expensive than gasoline over here, right now (~$1/gal higher). Isn't it supposed to be cheaper to manufacture?

Quote from DeadWolfBones :

Kinda ridiculous that diesel is so much more expensive than gasoline over here, right now (~$1/gal higher). Isn't it supposed to be cheaper to manufacture?

I was wondering about that when I actually looked at the prices at the gas station across the street. Diesel was about the same price as premium unleaded (I think about $7.74 per gallon).

My nan used to use an extremely good hypermilling technique. I REALLY RECOMMEND YOU DO IT! (not really, im kidding. it was extremely stupid what she done. dont do it)

Whenever she was greeted with a hill, she used to turn the engine off and put the ignition in number 1 and coast down the hill in neutral. I think that she eventually learned her lesson by crashing her brand new CLS into a bus stop when the steering locked up.

Ok, the hypermiling results are in, drum roll please.........

Pre-hypermiling driving techniques

11.56 gallons fill up
641.2 miles
55.5 mpg

Hypermiling driving techniques

11.39 gallons fill up
714.4 miles
62.7 mpg

IMO a MASSIVE difference, a 13% increase in mpg, well worth the increase, means I can get a good few days extra driving out of a tank of diesel, plus, driving like it makes it more interesting and less stressfull, don't feel the need to get everywhere as quick as possible.

Quote from tristancliffe :

The economy competitions people do are usually carried out by full throttle runs up to cruising speed, and then coasting for a bit, then full throttle, then coasting. This is the most efficient way of driving. The worst way of driving is how 99% of people drive to 'save fuel', by trying to not press the accelerator, and taking hours to get up to speed. So, by trying to save the planet, they actually harm it more.

Wouldn't flooring it make the mixture go a little rich?

Yes. What's your point? An engine is most efficient at peak torque WOT, when the mixture is richest.

Quote from tristancliffe :

Yes. What's your point? An engine is most efficient at peak torque WOT, when the mixture is richest.

(I was under the impression that WOT wastes a little gas for the sake of cooling)

edit: or am I confusing WOT with WOT+very high revs?

You use a little extra fuel as a charge cooler, and to gain complete combustion. You convert more fuel into useful energy than the extra added though, so the engine is most efficient.

+1% fuel => +10% output (figures made up to indicate the point).

Using less throttle injects less fuel, but makes less use of the fuel as well, so ultimately you need more to acheive the same amount of work.

To get from A-B or from A-B-C-D-...-Z using the least amount of fuel requires the greatest efficiency. FACT. How one gets that efficiency is the fun part. Pump up your tyres until the ride is awful, go slowly to avoid as much aero/rolling resistance (aero increases at the square of speed, whilst rolling resistance is pretty much a constant, with a slight increase with speed). Low grip, low friction tyres are also a possibility.

Personally I prefer to use my engine in an efficient manner, and leave everything else. Lots of throttle, lots of revs (relative to the general public, but not redlining, just using more of the efficient area of the torque curves), and then cruising at whatever speed I feel like - lowering my cruising speeds would help, but it also takes longer to get there and I'm an impatient sod.

The worst thing you can do is think that using less revs and higher gears will save fuel - it won't (and it will knacker your engine too!). Especially as the people that drive like that haven't done the other stuff - tyre compound, pressure etc.

Then we have the joy of bodykits - most standard cars come with plastic stuck-on parts designed to improve looks. They almost always increase drag, which decreases efficiency. Be green by removing them and incinerating them at very high temperatures (a bonfire isn't hot enough and will be counter-productive).


However, if you beleive what the government and the "advanced" driving organisations tell you, you might as well burn fuel in big drums in your back garden.

I see the whole picture now. Thanks.

P.S. danowat: what all did you do differently to get that extra 13%?

Quote from wark :

P.S. danowat: what all did you do differently to get that extra 13%?

Basically, broke as little as possible, but also, turned off engine if I felt that I would be sitting for longer than about 10 secs, and got up to about 56mph as fast as possible without going mad, basically using the torque band more efficiently, which is pretty bloody low on my car, 2000rpm peak torque.

Oh, also, increased tyre pressure to 38psi.

I reckon I could get to 65 mpg + with some slight driving style improvements