Eco driving incentive

[Dieselman]

Looking around the Eco-modder forum and I came across THIS thread and thought what a forward thinking company this USA lorry driver works for.

Just to give a scale of their savings, it's ~$20k per lorry per annum and they have 1100 lorries, so a saving of $22m per year.

Then it made me think just how much fuel could be saved if all UK companies operated such schemes for all company drivers in cars as well as lorries, and invested in Eco packages.

It reminds me of when fuel prices went sky high and shipping companies instructed Captains to slow down to save fuel. The savings were so huge that the companies were able to lease more vessels and carry greater tonnage and still save loads of money.

 

[Seamster15]

Interesting - thanks.

 

[wemorgan]

Looks like a good idea to me.

I remember the fuel protests of 2000 and seeing many executive cars and 4x4 doing 40-50mph on duel carriage ways. So people know how to save fuel when they have to. Not that driving prohibitively slowly is the solution, but just an example of willingness.

My other recommendation would be that all cars are fitted with prominent mpg gauges, showing current and trip efficiency. Too few people realise the consequences of their driving style in my opinion.

 

[st13phil]

Interesting link, thanks.

As the poster in that thread notes, driving technique can have a massive effect on fuel consumption, but as well as knowing the primary techniques to use you do need a feedback mechanism to help you get the best out of any given vehicle as some things are counterintuitive. For example, I've found that my W204 gives better fuel economy if I use slightly more throttle to accelerate than I would have expected, especially at low road speeds. If I'm really gentle on the throttle in those conditions then economy suffers. I suspect it's a result of energy being lost for longer in the torque converter if I'm really, really, light on the throttle at low speeds, but that's a pure guess.

I really miss the instantaneous fuel consumption readout that I had on my last two VW PD TDI's which would allow me to get a much better idea of what's going on

 

[Dieselman]

My other recommendation would be that all cars are fitted with prominent mpg gauges, showing current and trip efficiency. Too few people realise the consequences of their driving style in my opinion.

As the poster in that thread notes, driving technique can have a massive effect on fuel consumption, but as well as knowing the primary techniques to use you do need a feedback mechanism to help you get the best out of any given vehicle as some things are counterintuitive.

I really miss the instantaneous fuel consumption readout that I had on my last two VW PD TDI's which would allow me to get a much better idea of what's going on

You are both correct about driving style making more difference than speed per-se.
My car doesn't have a fuel computer so I as lacking feedback, which is one reason why I fitted the EGT gauge. It gives fantastic feedback of engine load.
st13phil: I think you might be correct about the 'verter losses.
Years ago we had a RR shootout and I plotted my gearbox losses, along with all other information gained.
The gearbox loss was higher at low revs load and reduced as more torque was fed through, then became higher again as the revs built up and engine torque reduced, even though power was increasing.

If you drive gently but in the range of maximum torque +1000 -500 rpm you should achieve high mpg.
I seems to have lost the data though, which is a shame.

 

[Mactech]

Interesting link, thanks

I really miss the instantaneous fuel consumption readout that I had on my last two VW PD TDI's which would allow me to get a much better idea of what's going on

I think they can be a really useful tool, but if we all understood fully what Newton had said, we could all get better economy without changing any hardware.
I don't let that stop me modding though!

Some people now think that a 'net force' is a blog.....

 

[johnsco]

Driving style in any vehicle makes a huge difference to fuel efficiency.
I've always used the old saying that "Your best brake is your accelerator ... Take your foot off it"

Taking your foot off the accelerator at the earliest opportunity as you approach a roundabout or a junction saves energy.
In a manual vehicle, knock it into neutral whenever possible and coast downhill or coast to a junction.

In a modern airliner, the computer calculates very precisely the optimum height and distance from the destination to cut the power, and then the optimum glide angle of approach to the airport.
This caused some problems recently in certain aircraft with fuel lines icing on the way down because so little fuel was passing through them.
Until mods are completed, the pilots have now been instructed to open them up every so often on the way down.

Mrs J and I run the same car ... the E300TD.
I try not to get myself in too much trouble by criticising her driving style.
It tends to be foot hard-down on accelerator or foot hard down on brake pedal.
Needless to say - It all wastes fuel - Not to mention wear and tear on brakes and suspension components.

Johnsco

 

[Dieselman]

In a manual vehicle, knock it into neutral whenever possible and coast downhill or coast to a junction.

That's not only bad practice but isn't it illegal as well.

The engine uses more fuel when in neutral than when on over-run as when on over-run it uses no fuel at all.

Anyway, I've just been into town in the Vrs and achieved a round trip economy of 56 mpg from cold with two stop offs..

 

[Dieselman]

I think they can be a really useful tool, but if we all understood fully what Newton had said, we could all get better economy without changing any hardware.

Wasn't it that the harder and quicker you press the accelerator, the quicker the seat backrest wears out..

I don't let that stop me modding though!

We need more details, such as have you altered the rear toe to be less toe'd in.
Fancy trying a grille block as a test..??

I note the facelift S-class has a full under-tray and the new E-coupe is the lowest drag production car ever, in low power diesel form (Cd 0.24), due to less cooling requirement.

 

[johnsco]

I've been told before that it's bad practice.
My dad used to play hell with me for it !

But, many truckers and PSV drivers have done it for years as a fuel saver, and if you do it with a bit of thought, it needn't be dangerous.
For example - I wouldn't do it descending a 1-in-4 with hairpins.

As to whether it's illegal, I don't know that it is.
If the vehicle ran away on a steep hill and it could be shown that the accident was caused by you not being in control of the vehicle, then that would certainly be illegal.
Just coasting in neutral, I don't believe that is expressly illegal by itself.

J

 

[johnsco]

Good old Newton.
As Mr Spock says ... You can't beat the laws of physics.

 

[Dieselman]

It certainly was illegal, made so after a runaway bus killed a group of marching soldiers on a hill years ago.

The vehicle should always be in gear for control and stability and will use no fuel at all.

 

[johnsco]

Coasting down hill or coasting to a stop in many automatics (not all) surely amounts to the same thing.
It's the brakes that slow you down, not the over-drive on the engine

J

 

[Dieselman]

Even in top it will raise the revs above town speeds, but try knocking it into 3rd, the engine will definitely slow you down then.
A diesel can provide significant engine braking.

Even an automatic isn't disconnected when over-driving, but I thought you were talking about manual cars when you said knock into neutral. Why would you do that in an auto.?

 

[Mactech]

We need more details, such as have you altered the rear toe to be less toe'd in.
Fancy trying a grille block as a test..??

Yes I have used less toe to good effect, but on race cars with solid rod ends and not the complient bushes found on road cars. You would really need some complex kit to work out the true dynamic toe on most road cars. I suspect most are within the nearest half house brick!
After 30 years trying I have given up trying to second guess aerodynamics.
Yes, the more air you put through the rad and engine bay the more drag, but without proper facilities you could guess very wrong!

 

[johnsco]

I was talking about "knocking it into neutral" in a manual.
I would never do that in an auto.
In fact - I'm not sure my auto would like it at all !!
Besides - There's really nothing to gain.

I agree that dropping the ratio in an auto will provide engine braking, but not all auto-boxes take kindly to doing this at any speed.
If you did it on the turbo-hydramatic 350 transmission on my old Chev, there was a very dramatic bump. You certainly got engine-braking on the overdrive then.

The point I was really making was that these are some of the ways to save energy, and I was using the examples in Post #7 as examples of how to save fuel.

J

 

[Will]

Hi John,

I think the point that Dieselman was making is that knocking a modern manual car into neutral (ie 'coasting') is a bad idea, as it isn't a good idea to coast (might even be illegal?) and it actually uses more fuel than if you left it in gear.

This is because modern cars have a microswitch on the throttle, so they know that your foot is off the gas and therefore don't require any fuel to be injected whilst the car is moving under it's own momentum/downhill etc. It's using the vehicle's momentum to keep the engine turning over.

By knocking it into neutral, the vehicle has to run the engine at idle as if it was stationary, hence burning unneccesary fuel.

Will

 

[johnsco]

Hi John,

I think the point that Dieselman was making is that knocking a modern manual car into neutral (ie 'coasting') is a bad idea, as it isn't a good idea to coast (might even be illegal?) and it actually uses more fuel than if you left it in gear.

This is because modern cars have a microswitch on the throttle, so they know that your foot is off the gas and therefore don't require any fuel to be injected whilst the car is moving under it's own momentum/downhill etc. It's using the vehicle's momentum to keep the engine turning over.

By knocking it into neutral, the vehicle has to run the engine at idle as if it was stationary, hence burning unneccesary fuel.

Will

I had a sneaking feeling that that is what Dieselman was saying.
Trouble is that I've never run a manual car that was modern-enough to have this facility.
So - In my motoring history - Coasting in manual cars has been a fuel saver.
In a modern-manual, it would obviously be counterproductive.

I accept the point about safety.
But - There are times when it is clearly safe to coast.

5.00pm ... I'm off home now
Catch you later buddies.

John

 

[kwakdonut]

I do hope you're never behind me going down a hill!!!

 

[kth286]

I had a sneaking feeling that that is what Dieselman was saying.
Trouble is that I've never run a manual car that was modern-enough to have this facility.
So - In my motoring history - Coasting in manual cars has been a fuel saver.
In a modern-manual, it would obviously be counterproductive.

I accept the point about safety.
But - There are times when it is clearly safe to coast.

5.00pm ... I'm off home now
Catch you later buddies.

John

On my 1995 124 320 Coupe there is a fuel cut-off function when the foot is off the accelerator. NIL fuel is used at those times.

I recently averaged over 32 mpg on a 250 mile weekend trip over several days using the tank top method of fuel checking.

None of the undertrays were fitted and the car has wider wheels.