coasting more efficient than regen: Audi

[MetroMPG]

Audi is producing a plug-in hybrid with a ~50 km / ~30 mile electric range which reverts to "normal" hybrid mode when the charge is depleted.

The most interesting thing I read in a review of the car was this (Neil will like this bit):

There is no regenerative braking when the driver lifts off the gas pedal in any mode except Sport. This means when the gas is lifted the A3 e-tron goes into a coast function, which mandates the use of the brake to get any slowing action. Audi says coasting is the most efficient route because it eliminates the need to consume power to return to speed after reducing it through regenerative braking.

Very cool. Of course, this freaks people out who want what they're used to:

That well maybe the case, but the total lack of “engine braking” did feel very strange.

However, in true German style, they offer a nice solution via the paddle shifters. You can get regen if you want/need it without also activating the friction brakes:

The saving grace is using the paddle shifters in any of the modes except EV does introduce regenerative braking and the slowing effect I wanted.

Source: Car Review: 2015 Audi A3 Sportback e-tron | Driving

[Frank Lee]

Regen is nice but especially for me- not much stop-n-go- coasting is far more efficient.

[jamesqf]

Originally Posted by Frank Lee

Regen is nice but especially for me- not much stop-n-go- coasting is far more efficient.

That depends. For me, most coasting involves descending miles of 6% or greater grades, so without regen (or engine braking) I'd soon be travelling faster than reasonable - to say nothing of speed limits. So much more efficient to put the energy back in the battery via regen, than have it wasted as heat from the brakes.

Fortunately I have a MIMA system, which like the Audi's paddle shifter, allows me to invoke regen whenever I want.

[Vman455]

If I remember right, the VW XL1 does the same thing--no regen unless the brake pedal is depressed. It would be nice for this feature to go mainstream.

[Cobb]

Again, having owned an insight and felt it out its a conclusion many come to. The least you use of the ima system the better your mpg is.

To cancel the auto braking regen of the gen 2 you just need to put light pressure on the throttle. To get more regen braking press the brake petal enough to turn on the brake lights. For more, click the left paddle while holding the brake petal.

[UltArc]

I am glad they didn't completely pull regen out. It really is invaluable sometimes- at some point we all need to slow down/come to a stop, and it just kills me to turn it into wasted heat.

[jamesqf]

Originally Posted by Cobb

Again, having owned an insight and felt it out its a conclusion many come to. The least you use of the ima system the better your mpg is.

Really depends on the sort of driving you do. If there are sizeable hills, it really helps. From my own recent experience (having the IMA essentially not working for a few months due to an unbalanced battery pack), it's worth at least 5 mpg from not having to downshift as much during climbs.

[Cobb]

Interesting, my assumption was the savings was from the lack of alternator and the higher voltage from the ima rotor converter to 12 volts was more efficient for the charging system. Even if the regen meter doesnt register, it does 7 amps at a bare min.

[niky]

I love it... excessive regen braking in some hybrids is kind of irksome... you want to minimize momentum loss rather than wasting doing regen. And if you really want the regen, a light touch of the brakes on most of these systems activates the electric regen braking rather than the mechanical brakes, so you still get it when you want it.

[vskid3]

One of my biggest complaints of my Prius vs the '06 Escape Hybrid we had before it is the regen on lifting off the gas. In the Prius, I have to give it just a little throttle to keep the regen away, the Escape coasted without throttle unless you put it in L "gear".
Its nice to know that manufacturers are actually looking at what works better.