Driving Economically
- Thread starter Dustydog
- Start date
- Nov 11, 2009
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My FIL had a similar low tech solution in his Hillman Minx. Knock it into neutral going down hill or when approaching lights or a junction. Scared us to bits.
- Jul 18, 2017
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The DKW also had the same system if you remember the DKW? Frightened the life out of me when I first drove one as part of our advanced driver training was to use the engine for gentle braking when approaching traffic lights, yield signs etc and where it was safe to do so.
To save fuel we do use the 1300 Corolla instead of the 3litre CRD as saves a lot of fuel. Hopefully with the diesel not being used often there will be no ill effects. Even during the lockdown we sued it for shopping once a week.
- Mar 14, 2005
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The answer is it depends on the situation, so potentially yes and no. However if you are freewheeling, then there is nothing for the engine to do, and if its not being driven by the momentum of the vehicle through the gearbox, so if the engine is running it must be using some fuel.... Where as if the engine is still being driven by the cars momentum, modern vehicles will actually cut the fuel completely.
With a free wheel, the car would roll further than if the engine is being turned by cars momentum due to the friction of the engine and if the cylinders are still being compressed which is what creates engine breaking.
Again some vehicles with modern ECU's and variable valve timing can hold the valves open to prevent compression. This also reduces engine breaking. but allows coasting.
The VAG PHEV (other makes might also provide similar features) system can also allow free wheeling when hybrid or electric modes. This can be disconcerting for the new driver, but you can also engage regenerative breaking which mimics engine breaking. But which is more efficient again depends on the prevailing circumstances.
- Jul 23, 2021
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All regular (not mild) Hybrid and PHEV and are functionally capable of "freewheel" for the ICE side. It's a basic requirement of the design that the ICE is able to disconnect from the drive train while the electric motor is running the show. How it's accessed is potentially different in each manufacturer. In my V60 PHEV, when you lift off the throttle, a mild form of engine breaking is induced in the electric motor, to recharge the battery and scrub speed as you would expect from a regular ICE car. To access freewheel, you apply a tiny amount of throttle, that sets the power delivery to "0", and the car will coast.
Interestingly, almost all modern EVs can be set to "coast" mode (where no additional power is fed to the wheels to overcome drag or gradient), but they don't actually freewheel. Permanent magnet brushless AC motors used in almost all EVs, either have to have the stator coil electrically disconnected (needs big switches) or have to have a balancing current fed to them to achieve zero loss. Tesla are fairly unique in that they use a permanent magnet motor on one axle and an electromagnet motor on the other, allowing the 2nd motor to be completely de-energised for cruise and freewheel. It's reactivated for regen braking.
Lots of clever software to make cars run these days!
- Jan 31, 2018
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Our Mini Clubman JCW coasted ie disconnected the gearbox from engine in green mode and it most definitely made a difference on rural and A roads-at least 2-3 mpg better overall average ie it usually did 34mpg but we managed 36 out of it if we used green mode-which was not that often tbh as the car was made for fun! As for it being dangerous that's not true and not how they teach you to drive these days-it used to be the case-use the engine braking to slow the caras brakes weren't reliable but they are now and learners are advised to do a fair bit of coasting ie upt to lights etc and use their brakes; as they say brakes are cheaper than engines or gearboxes.
- Jul 18, 2017
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However with an automatic you would simply lift your foot off the pedal if approaching traffic lights, yield etc. Although "coasting" you are still in gear and the engine is doing the braking.
- Mar 14, 2005
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Most vehicles that include a freewheel system, the engine is automatically disconnected from the drive, other wise it won't freewheel.
I had two three cylinder two stroke Saabs. Being two stroke the engines lubrication was provided by dosing the fuel. This meant that when going down long hills, with the throttle was set to idle and very little fuel was supplied to the engine, It also meant there was insufficient lubrication if the engine was left connected, so to prevent siezure it was recommended to use the freewheel, so the engine idled and had enough lubrication for tickover rpm.
- Nov 11, 2009
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Before Japanese motorbike two strokes introduced positive engine lubrication as the norm,, you had to watch the over run on the home grown products. If you think freewheeling in a car is hairy, a bike makes it much more fun.
- Jan 3, 2012
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Some years ago my wife use to own a Yamaha 125cc motorbike sometimes it would not start and pushing it and putting it in gear after a 12 hour shift just to get home it was fun but tiring.
- Jun 20, 2005
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You’re only the second person I have come across who drove 2 stroke Saabs. I wonder why a non eastern bloc country went for 2 stroke?
DKW were based in Saxony, Germany which became East Germany after WW2 until German reunification - the original Saab two-stroke was based on a pre-war DKW design.
- Jul 18, 2017
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I think DKW became Audi?
Is that why you always had a puff of smoke when you accelerated again? Another friend who was my boss had the 2 stroke Wartburg which I think had the DKW engine. He physically added2 stroke oil to the fuel tank, but for many years had the wrong mixture until I corrected him. No more smoke when driving up a hill etc.
- Nov 11, 2009
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A while back I posted a thread re GDR Towcar of the Year with this picture of a Wartburg near us. The guy now has another one, blue, right hand drive with towbar too, and in very good condition. He also has an original Tipo ( Golf Buster) and original Panda which he drove to North Cape. Will cost him a fortune to electrify his stable.
- Jul 18, 2017
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My friend had the estate version which he imported into Rhodesia and he did a lot of mileage in it. The front half shaft snapped and he was unable to sourced replacement so had to scrap the car.
That's the later 747cc three-cylinder engine mounted longitudinally in the 93, 94, 95, 96 - there was an earlier 764cc two-cylinder engine mounted transversely in the 92.
There were also experimental V6s, effective two three-cylinder engines mounted at an angle.
There were also experimental V6s, effective two three-cylinder engines mounted at an angle.
Someone told me about new Ford Focus, apparently it’s a 3 cylinder engine and when it’s warmed up driving it also drops to a 2 cylinder until you need more power.
BP
BP
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