Petrol Cost Cutting System Article Discussion Area

khizman

tomstickland wrote:

I've been monitoring my fuel consumption gauge for the last few weeks and also experimented a bit to find more fuel efficient driving techniques.

I've discovered that the easiest way to save fuel on journeys is in the deceleration when approaching a slow area. For example, if you are 1/2 mile from a roundabout and turn the engine off then you'd coast up to it and past it. You've travelled that distance using the momentum of the vehicle. Therefore if you back off the throttle a long way ahead of an obstacle then the fuel consumption will be almost zero for the distance up to the obstacle.
An engine on overrun (no throttle, but the car turning the engine at high rpm) uses no fuel - the ECU cuts off the fuel on overrun. My economy gauge shows infinite mpg on the overrun.

The important thing is that the earlier you anticipate and adjust the power input then the more you save.

My thoughts on the three phases are:

acceleration: very gentle acceleration is not the most efficient method. You need the engine to be at 30-70% load for best efficiency and the rev range somewhere between 1500 and 3500 rpm. 50% throttle actually provides quite brisk acceleration. But the engine doesn't spend as long in the acceleration state compared with taking 10 minutes to reach speed.

constant speed driving: fuel consumption scales with speed squared, roughly. The gauge in my car can be showing 45mpg at 85mph, but as soon as more than a few mm of throttle pedal are needed then the mpg drops right down. Doing a smooth, steady 70-80mph indicated with plenty of anticipation to avoid sudden acceleration will provide good fuel economy on mways.

general driving: anticipation to avoid the need for sudden acceleration, combined with a momentum conserving approach will save fuel. Jerky driving is wasteful. Leaving a bigger gap so you don't have to stop when another car pulls off will save fuel.

deceleration: as explained above, the earlier the power is taken off then the more that will be saved. The most efficient method would be to arrive at the obstacle with no speed after coasting the whole way with the engine off, but the normal method would be to arrive with some speed and the engine engaged and then brake.

I am not sure about turning the engine off, my mondeo book suggests NEVER to turn the engine off while in motion as
a) it will lock the steering wheel (security measure)
b) for the diesels it will cause the turbocharger to carry on working and lead to excessive turbo wear.

tomstickland

I'm not saying to turn the engine off.

but the normal method would be to arrive with some speed and the engine engaged and then brake.

I'm saying to take foot off pedal earlier. Engine off would be the ultimate, but foot off pedal is 99% as good.

I've edited my post because, I agree, it did look like I was advocating that.

kevbear

I'm a courier, based in Leeds, I drive a Vauxhall Combo Dual Fuel, Petrol/LPG.

As a LPG user, I'm astonished at the price variation per litre, EG locally I can get it at 36.9 PL, (was 32.9 until russia froze over) but once out of Leeds it gets up to 49.9 PL.

Also, Vauxhall and Ford seem to have stopped making dual fuel vehicles for the time being, almost as many LPG stations are closing or removing pumps, as new ones are being commisioned, and the government initiative seems to have stalled.

So much for a cleaner environment, I think we should be lobbying our local MP's to see what we can do to halp save our planet, and save money at the same time, I've already written to mine, still awaiting a reply.

What happened to all the publicity and hype that was around when LPG was released as an alternative fuel, it's the same with BioDiesel, every one knows of it, but you try to find a station which sells it.

Grrr

thomasheiser

Hi

I am sure everyone realises it but the best way for all to reduce the costs of your cars are to stop using them as much. I know many will say that you NEED to use them as much as you do but research has shown that cars are frequently used for journeys for which they are not really necessary (just look at how many comute through central london each morning alone in a big car). Walk, cycle, use public transport, set up a car pool..there are other options. As we move forward we are all going to feel the fuel pinch in a big way and really, as Bush says, the addicts need to start getting used to a different way of living.

Anyway - not really expecting to get anywhere with this post - I guess I was just surprised that there was no mention of this easy solution in the original article.

Best wishes

Thomas

charlieheard

thomasheiser wrote:

I am sure everyone realises it but the best way for all to reduce the costs of your cars are to stop using them as much. I know many will say that you NEED to use them as much as you do but research has shown that cars are frequently used for journeys for which they are not really necessary (just look at how many comute through central london each morning alone in a big car). Walk, cycle, use public transport, set up a car pool..there are other options. As we move forward we are all going to feel the fuel pinch in a big way and really, as Bush says, the addicts need to start getting used to a different way of living.

Thomas, I couldn't agree more! When people use their car, they don't realise that it costs them at least 50p per mile in fuel, wear and tear, depreciation, etc - more if you're using a bigger car. A ten mile connute to work is £5 per day, £25 per week.

When I lived in SW20, I used to cycle to the City every day. I was beathing less fumes than those enclosed in their cars, I was almost as fast when the traffic was moving, and much faster in slow traffic. It took 45 minutes for 10+ miles, so I arrived at most 5 minutes behind a car when they had a good journey, and much earlier when there were problems, tube strikes, bomb scares, etc. Yearly cost, about £100 in servicing. Fitness gain, immeasurable. Even the train took over an hour.

As you said, all it takes is some change in thinking. I would take all my shirts in on Monday and back on Friday, always leaving a spare and I left 2 suits at work. I would have a shower at work instead of at home. No problems...

charleyfarley_3

Kevbear the courier - Have you found any biodiesel sellers?
I understand that there are a few including Tesco (certain branches - hardly any though). Generally, I understand that the Government need a kick up the exhaust as there is currently no incentive for the big boys to promote alternative fuels due to development not receiving any subsidies.
Anyone out there know any more on this subject? Not only to reduce costs ie biodiesel should cost a lot less per litre than fossil fuel - ie grown and processed in UK, no wars to fight over it (currently) but carbon neutral to boot. Well done for raising this issue.
Turn your grrrrrss into purrrrssss!!

robin1306

I to used to fill up with supermarket petrol but then switched to shell and got a measured extra 56 miles a tank!!! then I added some the oil treatment slip stuff and got another 25miles out of a tank full. I was a cynical sceptic till now. I put some the slip stuff into the fiesta as well and that stopped burning oil each month and now runs better on shell as well. Fortunately we have a local price war with asda petrol and Morrisons petrol so the shell and esso garages compete with them and we the customer get the best deal out of it all!!!!

tomstickland

thomasheiser wrote:

Hi
I am sure everyone realises it but the best way for all to reduce the costs of your cars are to stop using them as much.

Yes, you are correct.

fuel cost = distance * fuel_per_distance * cost_per_unit

so you need to do all three
-reduce distance travelled
-increase mpg
-reduce petrol cost

Short journeys with multiple stop starts are the worst offenders. I want to move within cycling distance of work.

shuwaz

I have been told that veggie oil works fine on diesel engines.

Apparently you should start of gradually until you feel the car engine begin to splutter slightly. Then you will know that you have breached your optimum mix of veggie oil and diesel.

I haven tried it yet though because i travel 120 miles a day and cant risk breaking down...

:rolleyes:

It would be nice to know if anyone has tried it yet?

charlieheard

shuwaz wrote:

I have been told that veggie oil works fine on diesel engines.

Apparently you should start of gradually until you feel the car engine begin to splutter slightly. Then you will know that you have breached your optimum mix of veggie oil and diesel

On more modern engines, the tolerances are very fine, and they need the specific properties of diesel fuel to lubricate the pumps, etc. You can run on a mixture, but I'm sure that it would mess up any claim if the system failed. If you get as far as the car stuttering, you may be looking at cleaning out the whole fuel system and rebuilding the very high pressure pumps on modern cars (up to 1800 atmospheres). It will only cost you between £400 and £1000 to replace them, like when you accidentally put petrol into them :rolleyes:

Vegetable oil will work on older deisel engines. You can even use used oil from a chip shop, as long as you filter out ALL the fine particles. On older cars, the mixture is less crucial, and I am aware of many people that run cars like older Mercs on vegetable oil - an older deisel engine will run on just about anything that will burn.

Just be aware that if you use any oil as fuel, you will need to pay fuel duty to HMRC. This means that most vegetable oil is not worth it unless you want to break the law and not pay the tax. But then you're in a spot of bother when stopped by Plod with your car smelling like a chip van

To sum up, I wouldn't try it on newer cars. You can do it on older cars, but unless you have a very cheap supply of oil (or you run a chip van), it's not really worth it