Cruise control hammers the range

[TonySpice]

Started commuting with a FFE.

Most of my ride is NJ I-95 and the cruise control appears to hammer the driving range.

Is that normal - I had assumed cruise control would be the most efficient option, although looking back on it not sure why.

 

[paw160]

Likely depends more on your cruising speed and road grade. Highway driving isn't as beneficial to an EV as it is to an ICE. You really don't get much coasting/regen opportunities at highway speeds combined with the higher speed...

 

[TonySpice]

Likely depends more on your cruising speed and road grade. Highway driving isn't as beneficial to an EV as it is to an ICE. You really don't get much coasting/regen opportunities at highway speeds combined with the higher speed...

Yep, I'm doing 60 - 65 for most of the journey.

 

[WattsUp]

I've done many trips at around 65 mph and feel I could easily achieve the advertised 76 mile range. I've often come close, going 65 or 70 miles with still around 10 miles remaining at my destination.

In my experience, on level freeway, maintaining somewhere between 60 and 65mph, energy usage averages out around 256 Wh/mi. This is the level you need to maintain in order to achieve the "full" 76 miles of range on a 100% charge.

I would suggest that your range issues have nothing to do with using cruise control or not. I actually use the cruise control for long-distance (indeed most) driving because it does a much better job of minimizing and stabilizing energy usage than I could. (The same holds true in ICE vehicles, too.)

I would check other things...

• What is your average energy usage? (Again, for "full" range, your average should be 256 Wh/mi or less)
• Be honest, are you "cruising" significantly over 65 mph for some of the trip? (No can do for full range)
• Are you going uphill? (Even a small grade over the entire trip will eat up range)
• Are your tires inflated properly? (They should all be 38 psi cold)
• Are you also using A/C and/or heat? (Heat does hammer range)

 

[davideos]

I find it very hard to believe that cruise control uses more power. It should be the opposite and with very little difference. Be sure you are comparing the same driving condition, route, and direction. And compare the watt/mile shown on the left display when you turn the car off at the destination.

 

[WattsUp]

I find it very hard to believe that cruise control uses more power.

It doesn't.

 

[jmueller065]

If you are not sure how to get the watt/mile figure:
Go into the trip meter on the left display and hit the right arrow button to get to the trip meter settings and select the Enhanced trip meter.

 

[az erik]

I find it very hard to believe that cruise control uses more power.

It doesn't.

Oh but it does. Just like it does on all cars. The cruise it's self doesn't, it's actions do.

Case in point i8 on the way back from San Diego to PHX. it's a 4% uphill grade. You set the cruise on any car it will keep you at 75. It'll slam the peddle down in order to keep you there. The FFE is no different. You can see it reflected in the 1 minute energy consumption meter. I run the same route once a week. I'noted a 75kwh/ more use with the cruise. That said it's because in the uphill bits I'll let the car come down to 62 or whatever because I'm not paying attention. With the cruise set it'll hover in the uphill usage around 350, if I'm driving it's usually 275.

This is the way the cruise is designed. There arn't "lazy" cruise controls. They are agressive. Same thing happens with ICE cars, you just don't realize it easily. That trip from SD to PHX in my trucks, I'd get 3 to 4 mpg more without the cruise. My ETA suffered as much as 30 minutes. Yes I made better time at the expense of more energy. Same would happen if I held my foot 2/3 down like the cruise did to keep me at 75.

 

[WattsUp]

I find it very hard to believe that cruise control uses more power.

It doesn't.

Oh but it does. Just like it does on all cars. The cruise it's self doesn't, it's actions do.
...
I'd get 3 to 4 mpg more without the cruise. My ETA suffered as much as 30 minutes. Yes I made better time at the expense of more energy. Same would happen if I held my foot 2/3 down like the cruise did to keep me at 75.

I get what you're saying, but it doesn't mean that cruise control uses "more" energy than a human driver would by executing exactly the same actions (if that were possible).

The cruise control does nothing different that you could do with your foot if you had instantaneous reactions to the speedometer and could maintain a perfectly constant speed. If the driver wants to cruise up and down hills at a constant 75 mph, the cruise control will do that more efficiently than he could. Even on level ground, the cruise control will maintain speed more efficiently than a human. (Again, this goes for all vehicles types.)

The nice thing about EVs, though, is that, over hilly terrain, sure you sure use energy going up hill, but you can actually gain some back going down. In other words, conceptually, driving at a perfect 75 mph over hilly terrain (with equal uphill and downhill portions) should only be slightly less efficient the driving 75 mph over flat terrain. It's reality, it's not a perfect conservation of energy (since regen is not 100% efficient), but it sure beats doing the same in a gas vehicle!

In any case, the primary reason your MPG was better going slower in your truck was because you were going slower.

 

[az erik]

In any case, the primary reason your MPG was better going slower in your truck was because you were going slower.

Exactly. Some people don't realize (I knew this which was why I typed it up) that the cruise doesn't slack off and that the person does, or can. Either way the cruise just says apply "gas" unit we reach X speed again.

I couldn't use the cruise in my Lightning, the friggin thing would pound the peddle down half way and overshot the mph then back off, it'd drop past the set speed, it'd hammer it again. 1/2 peddle in a 600+hp vehicle is violent anyway you put it.

 

[davideos]

I agree on the comments above. I believe the cruise control will only save energy by eliminating a driver's need to "catch up" to the target speed when it drifts below that target. In this case, the added efficientcy will give you more miles/kwh, but only when compared to a driver doing the same thing.

I had to do a longer than normal trip a few months back and I used the cruise control to set the speed to 65 and keep it there. If left to my own devices, I'd be going 75 or 80. In this case I got much more distance than if I did it myself.

In summary, I would suggest that cruise control is just a tool...not necessarily a fuel saver. It just depends on how you use it.

 

[WattsUp]

In summary, I would suggest that cruise control is just a tool...not necessarily a fuel saver. It just depends on how you use it.

Yup. I use cruise to ensure I keep a nice steady 65 mph on the freeway and average 256 Wh/mi (or wattever I'm trying to achieve). I find cruise control helps me be a more efficient driver than if I didn't have it.

 

[WattsUp]

I agree on the comments above. I believe the cruise control will only save energy by eliminating a driver's need to "catch up" to the target speed when it drifts below that target. In this case, the added efficientcy will give you more miles/kwh, but only when compared to a driver doing the same thing.

Yes, I would rather have a computer maintain my speed than me.

Imagine all the gasoline that would be saved if everyone driving ICE cars would learn how to use their cruise on the freeway. I see so many drivers with the "gas on" and "gas off" yo-yo driving style. They are repeatedly accelerating (in bursts) and then drifting slower on the freeway. I do not understand their thought process.

 

[TonySpice]

Thanks Erik. That's what I had felt. I've always had the assumption that cruise control drives the car more efficiently than a human (not sure why) but if that's not the case then it could explain the difference I'm seeing with it on vs off. I have a few up gradients in my commute and I do get that sense of the car "flooring it" and going faster than I would try to go.

 

[WattsUp]

Some people don't realize (I knew this which was why I typed it up) that the cruise doesn't slack off and that the person does, or can. Either way the cruise just says apply "gas" unit we reach X speed again.

Hmm, that doesn't appear to be the way the cruise in the FFE works (nor in my ICE vehicle, for that matter). The cruise in the FFE seems to precisely modulate the balance between acceleration and regeneration exactly as a "perfect" human would, if they were trying to maintain the set speed. I find nothing "violent" or "on/off" about it.

In any case, the cruise does a much better job of efficiently holding the set speed than I could. I achieve a lower Wh/mi using the cruise than without. I use cruise practically everywhere I need to drive at a constant speed, even between lights in some cases.

 

[jachady]

The factory cruise does the best at maintaining your vehicles speed but it doesn't take into consideration other factors, mainly hills that affect fuel economy. When you start up a hill the cruise will allow a 2mph drop before reattmpting to maintain the speed. To get the best fuel economy with gas or EV, you should allow the speed to drop further, around 5-6 mph.
So say you're driving with the cruise set at 57 mph. While heading up the hill simply hitting the set- button 5-6 times dropping to 51 mph. Then when heading down the other side, regain your speed using gravity to assist, hit the set+ button to get back to your original speed (57 mph). If you are in a rolling hill terrain, I will raise the cruise speed by 2 mph to 59 mph while heading downhill to give me more drop while climpbing the next one. When dropping the speed I'll watch the energy usage guage and when it starts to climb I'll hit the set- button.
Of course there are exceptions to this, like if you're in traffic and don't want to piss off everyone behind you, or you're climbing a mountain and dropping the 5-6 mph won't really help. But if you have the time and can multitask you can really pick up economy in any vehicle.
Ford actually programmed a bit of this in into their current hybrids and Enegis', they call it ECO-Cruise. That system tries to prevent the transmission from downshifting while climbing a hill and allows for more loss of speed.

 

[Josephus]

My wife was surprised by how efficient the cruise was compared to her ninja zen driving.

Cold weather with the heat and fan blowing will add 50-75 watts/mile for me.

 

[EVA]

I sure hope you all that reduce your speed going up a hill drive in the FAR right lane, or with nobody within miles behind you.

 

[WattsUp]

Cold weather with the heat and fan blowing will add 50-75 watts/mile for me.

watt-hours/mile

Wh stands for watt-hours.