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Discussion Starter · #1 ·
From reading this forum it seems that most folks think the best way to achieve max battery range is to drive in Hill 1 mode. However I find that this severely cuts down on my ability to coast, which requires that I keep my foot on the accelerator (guess I can't call it a "gas pedal"!) longer than I otherwise would.

I haven't been looking at the status screen to run the test (too busy looking at the road), but have others done the math? Is the energy savings you get by the regenerative braking in Hill 1 worth the cost of needing to accelerate more than you otherwise would need to?

I live in Silicon Valley, which is almost entirely flat. A few rolling hills here or there, but nothing that would make it worth the effort to constantly switch in and out of the various modes.

And what about Hill 2? I have only used it seriously once - while in Hillsborough going from 280 into town (for those of you who know Silicon Valley) and it was fun to watch the miles add up, but otherwise I find it too much of a drag. And, of course, the extra miles were eaten up when I headed back to 280, which was less fun.

Thoughts?
 

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The starting part of my commute each morning is a decent down an long and steep street in San Francisco. I find that Hill 1 lets me keep pace with traffic that is trying to race down the hill without regard to the fuel consumption while building up the battery reserve. I have tried Hill 2, but the cars behind me start getting very impatient and irritated.

This weekend I was driving on Skyline road and came down Woodside road on Hill 2 since there was not a lot of traffic and managed to capture about 3 miles worth of battery reserve before I got to the 280 interchange. It does actually work really well, but with any sort of traffic, it gets very nerve wracking.

On the highway, I have found that Hill 1 lets me drive without using the brakes by letting off the accelerator a bit earlier and getting the braking effect. Hill 2 makes me uncomfortable because the car feels like it is decelerating very rapidly and I am always worried about getting hit from behind.

Bottom line is that you can very easily find the point where you can get the same effect as coasting in Hill 1 by keeping the Accelerate/Generate indicator in your peripheral vision and keeping the "needle" vertical. I have not found it particularly distracting and once you get the feel for it, you don't even need to look at the dial anymore.
 

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I use it for the stop an go traffic on the roads around Huntsville, AL because it allows the car to react before I get on the brake. Of course, when it is open road I use cruise control which automatically reverts the car back to non-Hill mode.
 

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Back in my days with a manual, "Hill 1" was like downshifting from 5th to 4th and "Hill 2" was like downshifting from 5th to 3rd (in terms of amount of engine braking) and I would do either or both as needed. I think the thing to do is leave it in D if you're feeling lazy and on the freeway (and it's clear enough), and Hill 1 or 2 if you're on side streets with lots of stop and go and/or hills.

But I haven't got mine yet, so that's theory rather than practice. :)
 

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I have been leaving mine in Hill 2 pretty much all the time so far. Living at 8,000 feet, every road is either up or down, nothing is flat, and the regen braking is a welcome addition. The only problem I have is having to remember to put it into Hill 2 after each start, but I'm getting used to it.
 

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Skibum said:
Is the energy savings you get by the regenerative braking in Hill 1 worth the cost of needing to accelerate more than you otherwise would need to?
I have generally agreed with skibum. Hill mode is obviously good for hills, but when you start talking about using it as a default mode around town, my internal "logic math" has always suggested to me that, on level terrain, this is a zero sum game at best. Yet, I might now consider that, all things being equal, if you were going to slow down anyway using brakes, at an equal rate that you are now using H1 for, then you probably are getting some advantage. Why? Because upon accelerating again, the car isn't any more "held back" by the H1 mode...that is, the engine braking is not in force once you have re-engaged the accelerator, so therefore your energy use from your current state going forward is exactly as it would have been if you were in normal stealth mode, but meanwhile you did pick up some regen braking power. And you are not "needing to accelerate more than you otherwise would need to". But that is all predicated on the assumption that the amount of DEceleration you caused in H1 is no more than you would have using just brakes in Stealth mode. And THAT is the key to agreeing in general with skibum... I feel like H1 is often slowing the car more than I would normally if using just brakes, when in a freeway drivng situation that really just requires a little sporadic coasting.

What is really interesting is that, in the end, we're talking about a couple miles of extra range, in a car that has a range extender anyway. We're all so retentive about this stuff, it's wonderful. Good to be part of early-adopter geekdom. ;)
 

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One thing I noticed is that if you change from 'D' to 'R', the car's braking mode will be lost and when you switch back into 'D' braking mode will be normal, e.g. if you're driving down a road and decided you're going the wrong way, so you make a couple point turn, reverse, then go back into 'D', the Karma puts you back into normal braking rather than the Hill 1 or Hill 2 that you had before you changed into reverse. Wish that it could remember previous braking setting so you didn't have to remember to change back...
 

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Discussion Starter · #8 ·
Dave_Car_Guy said:
Skibum said:
Is the energy savings you get by the regenerative braking in Hill 1 worth the cost of needing to accelerate more than you otherwise would need to?
But that is all predicated on the assumption that the amount of DEceleration you caused in H1 is no more than you would have using just brakes in Stealth mode. And THAT is the key to agreeing in general with skibum... I feel like H1 is often slowing the car more than I would normally if using just brakes, when in a freeway drivng situation that really just requires a little sporadic coasting.
Right, I was not referring to the case where you need to slow down. I was more thinking about the situation where you would normally ease off the "gas" and coast for a bit - in H1 or H2 you then slow down and need to pick up that speed again.
 

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I assume the brake lights do not come on when using Hill mode.
In Hill mode 2 it is not really necessary to use the brake. Is this not dangerous for traffic coming from behind ?
They may not see that the Fisker is slowing down more than an 'old fashioned' car that needs to use its brake.
 

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flying dutchman said:
I assume the brake lights do not come on when using Hill mode.
In Hill mode 2 it is not really necessary to use the brake. Is this not dangerous for traffic coming from behind ?
They may not see that the Fisker is slowing down more than an 'old fashioned' car that needs to use its brake.
It's no more or less dangerous than downshifting a manual transmission one or two gears. The car decelerates and there are no brake lights. I'm sure that unobserved deceleration from downshifts has led to the occasional rear end collision, but generally speaking people have managed to downshift manual transmission cars without brakelights for 100 years with reasonable success and safety.
 
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