Freewheeling to save money

Iceweasel

alastairq wrote: »

All skids are a loss of control.....even if done deliberately [a deliberate loss of control]...

No, No, and thrice No!

Did you never see Roger Clark at full bore using opposite lock?

That was done deliberately - but it was skill - not a loss of control.

Not that I advocate the average driver to try it, mind you.

Having said that, many do - although nowadays it seems to be called 'drifting'.

Ultrasonic

OK, I'll be honest and admit to coasting in neutral sometimes to save fuel (and yes it does, Almilller gave a fairly decent summary above). I will in particular do this in queuing traffic, where there is never any question of needing to suddenly accelerate to avoid danger. The only other time I'll do it is on roads I know well when there is no other traffic about, when slowing down for a roundabout or junction.

SteveJW

Have a look at http://www.volvotrucks.com/trucks/uk-market/en-gb/trucks/volvo-fh-series/key-features/Pages/i-shift.aspx

Scroll down to Let-IShift save you fuel, second paragraph


"automatically disengaging the engine to make use of the truck’s momentum instead of fuel"

goonarmy

Be out of gear is not unsafe due to the lack of ability to acclerate.

alastairq

No, No, and thrice No!

Did you never see Roger Clark at full bore using opposite lock?

That was done deliberately - but it was skill - not a loss of control.

sorry, you're off the mark there.

An induced skid is a deliberate loss of control. The skill comes from the driver managing that loss of control to achieve an end.

Anything a vehicle does which the driver did not intend...is an unintentional loss of control.

NO matter how brief the event.

I post as someone whose job partly involves what I mention in the first line of my last post...amongst other skills.

Limey

alastairq wrote: »

SAAB were renowned for fitting a freewheel device to their 95 & 96 range....[as were several East German manufacturers...Wartburg for one].... as an economy device.

When engaged, once the gas pedal was released, the freewheel took over...however, drive was re-engaged as soon as the gas pedal was brought back into use.....without a shock or jolt to the transmission.

Took a bit of getting used to, to find one wasn't slowing down as one thought one should, when off the gas...

I had an old Saab 96 V4 and yeah the freewheel device was 'interesting' when engaged on the motorway and bloody terrifying on a hill. :rotfl:

Bongles

alastairq wrote: »

sorry, you're off the mark there.

An induced skid is a deliberate loss of control. The skill comes from the driver managing that loss of control to achieve an end.

That seems an odd definition of control you've got there. If the position, motion and attitude of the vehicle are a result of the driver's control inputs and they are the position, motion and attitude that the driver intends, in what way is the driver not in control?

Bongles

Ultrasonic wrote: »

OK, I'll be honest and admit to coasting in neutral sometimes to save fuel (and yes it does, Almilller gave a fairly decent summary above).

I'm not persuaded by it yet, although I am open to persuasion. Almillar asked:

almillar wrote: »

Do you need to
a) use the brakes (and engine)
b) use just the engine
c) use neither - coast/freewheel

and went on to explain how, if you can do c, it might be better than a or b. However, it seems theoretical rather than practical to me. I can't picture a real life situation where you might do c. I note that losing some speed though coasting and then using the brakes to lose more is not c, it's something else (let's call it d ). And I don't think d is better than a or b - at least I don't think it's supported by the argument used to support c.

Ultrasonic wrote: »

I will in particular do this in queuing traffic, where there is never any question of needing to suddenly accelerate to avoid danger.

Trying to picture this one. I think you must mean a moving queue - presumably moving at fairly constant speed (rather than a stationary or stop-go queue)?

Ultrasonic wrote: »

The only other time I'll do it is on roads I know well when there is no other traffic about, when slowing down for a roundabout or junction.

Do you not find that on approach to the hazard you also need the brakes at some point? Are you really starting to slow from even further away than the distance your momentum would take you if you lifted off and stayed in gear?

Jamie_Carter

Iceweasel wrote: »

Some time around the mid 90s I would think.

Are there any new cars still with carburettors?

From what I understand all cars have been fuel injected since all cars had to have catalytic converters. Something to do with the unburned fuel damaging them I think.

alastairq

Bongles wrote: »

That seems an odd definition of control you've got there. If the position, motion and attitude of the vehicle are a result of the driver's control inputs and they are the position, motion and attitude that the driver intends, in what way is the driver not in control?

Because the wheels & tyres are intended for gripping the road surface.

Therefore if they don't grip the road surface, there is a 'loss of control'....ie, a skid.

All skids occur as a result of driver input.

[Especially if said driver fails to identify, and act upon, the sight [or suspicion ] of a less than suitable road surface.]

Whether that input is intentional [as with rally drivers using the skid to scrub off speed and point the car in a new direction]...or unintended...the fact that the wheels/tyres are not doing what they are intended for, means a control-loss.

As I have said, where a skid is deliberately induced, the skill of the driver [at vehicle control, not interaction with other road users....let's not confuse the issue?]......lies with managing that loss-of-control.

For the rally driver or circus-trick driver, should the situation change, recovery from the loss-of-control is another thing altogether.