coasting more efficient than regen: Audi

[jamesqf]

Originally Posted by vskid3

In the Prius, I have to give it just a little throttle to keep the regen away...

The same is true of the Insight, BUT if you have a ScanGauge or similar, you might discover that the 'little throttle' is not actually sending gas to the engine, it's just cancelling the regen. At least that's the way the Insight works, and it would seem like an obvious thing to do in order to provide a driving experience that's 'just like a normal car'.

[NeilBlanchard]

VW will have this free wheel coasting on the eGolf, and there you get some/more regen by bumping the shift lever. The Smart ED also has paddle selected regen with free wheel coasting as a $200 option. And the Fit EV does this in Eco mode, as well.

Some EV makers "get it"! I'm sure it would take getting used to, and you do have to learn how far your car coasts to take full advantage of it, but at least there is no learning required to *get* free wheel coasting! Just lift your right foot ...

[user removed]

What is old is new again.

Freewheeling circa 1931.

1931 and 1932 Plymouth PA cars

regards
Mech

[Joggernot]

Originally Posted by Old Mechanic

What is old is new again.

Freewheeling circa 1931.

1931 and 1932 Plymouth PA cars

regards
Mech

After reading this and a couple links, I find I like it. I assume no modern ICE car has this? Excellent technology for the early 30's.

[user removed]

In one of the few cases where a vehicle capability is made illegal, Virginia outlawed the use of freewheeling after accidents where brakes failed coming down the US routes that go over the appalachian mountains. US 50 and US 33 are two of the routes and I can tell you from firsthand experience that they can get pretty hairy in a new car, much less non power assisted 4 wheel drum brakes where the fluid could reach boiling point. It is my understanding that the freewheeling could not be disengaged while the car was moving.

The hilarious thing is I don't think the law was ever repealed, so technically a Prius is illegal to operate on those same roads, by the strictest interpretation of the law, which will never happen.

regards
Mech

[gone-ot]

NEUTRAL in a Prius CVT is STILL actually mechanically gear-engaged, because two of the three shafts are turning in opposite directions at exactly the same speed, but ALL the gears are always meshed.

[RedDevil]

And Neutral in the Insight is actually Neutral, with the engine ticking over at Idle where it would DFCO if it were left in D.
So it will actually use more fuel in Neutral then when carefully matched with the throttle to defeat regen. Or given a little more throttle to prolong the glide under mild electric assistance, or deliberately left unthrottled to get regen while mildly braking to prevent overshooting the destination. There is some flexibility in that range to play with.

I like the regen though because it will use the power to accelerate again, and you don't want it to regen while maintaining speed after acceleration to replenish the battery while you could have gotten that charge from deceleration.

Also, the Insight is a keen roller. I generally need to decelerate harder than just coasting when leaving the highway etc. The deceleration under mild regen is about the same as the other cars do when they just lift the throttle, or maybe just a fraction more.
The point is, I can roll along with the other traffic leaving the highway without having to touch the brake pedal, if they don't brake too.
I dislike having to light the brake lights when just losing speed at the same rate as the other cars when they don't brake. So I am happy with the mild regen.

IIRC the Tesla model S can be driven with just the accelerator pedal under normal conditions as it will regenerate strongly when you lift off completely. I wonder if that makes the brake lights burn?

[elhigh]

Originally Posted by Joggernot

After reading this and a couple links, I find I like it. I assume no modern ICE car has this? Excellent technology for the early 30's.

Voila:


Here's a view of the little freewheel unit clearly visible along with the attached diff:
http://www.vintagesaab.com/images/freewheel.jpg

The humble and mighty SAAB 96 bore a freewheel throughout its production run, right up to 1980, even though the original reason for its inclusion, the old two-stroke three-cylinder that needed not to overrun its fuel-oil mix during closed-throttle deceleration, had been out of production for over a decade.

The freewheel could be a service hassle. Some owners fitted springs under the handles of theirs, to hold them in a locked position. Some - namely, Dad - tied a length of twine from the handle to the handbrake pivot. Whatever it takes.

Just one fine example of another hapless SAAB owner:

[Ecky]

In the 1st-gen Insight, there's some computer logic that determines whether or not to regen when your foot is off the gas, and I think it mostly has to do with battery level. In city driving it likes to be at around half charge, and will cut off deceleration regen above that, but get up to highway speeds and it will take the meter to full. It's a slug to drive without assist so I'm rather glad that just it's able to stay topped off with only decel regen.

[MetroMPG]

More coasting news from Audi:

They've dropped the CVT in favour of a new 7-speed DSG with a "coasting function" in a revised ICE-powered A6 high efficiency model.

Facelifted Audi A6 to include new 109g/km ultra model | Fleet World