[Feddar]

I have searched the forums, and I'm surprised that this does not come up. I am wondering what is the most efficient speed to drive on the highway to maximize your range. I'm thinking 105 km an hour is doing well.

 

[Packard V8]

There's maximize the range which means slooooooooower is better. IIRC, aero drag increases by the square of velocity, so your 105km/hr (65 MPH) as maximizing range is dreaming.

Then, there's minimize the net travel time when a way charge is involved. That's a complex multi-variable regression analysis which has been discussed here many times. Some can demonstrate their logic shows faster is better.

The bottom line tradeoff in normal operation is one's patience for lower speed to achieve maximum range. In an emergency situation where range deficiency may strand one in dangerous circumstances, slowly, slowly.

Just yesterday, I observed a Prius who pulled over on the shoulder twice to let the normal 60 - 70 MPH two-lane highway traffic proceed so he could maintain his preferred 50 MPH.

jack vines

 

[rawb]

Highway speeds are not the most efficient speeds. The slowest speed you can manage would be most efficient.

One day last winter I was caught out 60km from home with 40km of indicated range. Speeds around 50-60 km/hr seemed to be the most efficient. That may vary in summer with less dense air, but I'll bet it's always well under 100 km/hr.

Yes, I got home that day.

 

[discodanman45]

The most efficient speed to drive on the highway to maximize range is about 20 mph. Eventually someone will kill you because of road rage, but that is the answer to your question.

 

[redpoint5]

The question itself is a bit of an oxymoron. As others have pointed out, the slower you go, the greater your range in nearly all use cases unless it's -20 outside and you're debating if it's better to go 10 MPH or 20 MPH (heating the cabin consumes a sizable amount of energy when it's cold out).

I've run some numbers on the Bolt regarding completing long distance trips as quickly as possible, and assuming there is a DCFC placed exactly where you need it all along your route, the most time efficient speed is 75 MPH. Any faster and you're expending energy faster than you can put it back in at a DCFC. In other words, the time you save by driving above 75 MPH is more than eaten up at the charger.

With cars that can charge at greater than 55 kW, there's practically no limit to the most time efficient speed you can travel. Driving faster will get to the destination faster.

 

[Feddar]

Thanks guys. We are now sticking to 100kph.

I wonder why our ontario rest stops don't have charging stations. Tim Hortons is there, and they have the contact, don't they?

 

[discodanman45]

I drive 98% of my driving on highways, the majority I drive about 120 kph. I have an average of 3.8 mi/kWh or 6.1 km/kWh. I do run into occasional traffic that helps out my efficiency and I hardly ever use the heater. I just use the seat warmer and heated steering wheel on cold days. However in my area it only gets below 0 degree Celsius for a few hours per year.

 

[SudBolt]

Here's some light reading I found. Pretty detailed stuff.
http://www.roperld.com/science/ChevyBoltRange.htm

 

[SudBolt]

Thanks guys. We are now sticking to 100kph.

I wonder why our ontario rest stops don't have charging stations. Tim Hortons is there, and they have the contact, don't they?

I agree. It would just make sense to have dedicated EV DCFC charging stations at the Enroute stops. I'm sure they could pull a dedicated line in for the chargers and not have to rely on a de-rated source.

 

[RichardC]

I have found that 60mph or 100 kph to be my best trade off between time and range. Traveling on secondary roads at 50 to 55 yields better range, but only if you don't go through too many small towns and local traffic isn't going 35 in a 50. In these cases the stop and go eats up the same kWh as just doing a constant speed on the highway. It is a more pleasant drive though.

 

[GJETSON]

I have found that 60mph or 100 kph to be my best trade off between time and range.

Don't know where you live, but in Virginia there are no 60 mph highways that I know of. Two lane roads are 45-65 mph. Divided highways are 65-70 mph. And of course, if you drive the speed limit, in the right hand lane, you will be passed by every vehicle.

 

[RichardC]

I usually manage to find a semi going 60 mph and stay behind them as long as I can. Not to hypermile, I don't get that close. Just so they take the "heat" from passing cars. Often a U-haul trailer will be going 60. If I run out of trucks or trailers I go 65. If I'm getting caught in a pincher move I go as fast as **** to get clear of it! I'm sure I've surprised a few people when a Chevy Hatchback is all of a sudden a quarter mile ahead.

 

[Feddar]

I've had the Bolt for over a year. We just completed our first out of house charging! In Kingston, halfway between Toronto and Ottawa. It took an hour to get an 80% charge. Not quite as advertised...

But I can't complain, for a $15 charge to get me to Ottawa. I used to be happy with $50 in my smart car.

 

[banksdad]

I usually manage to find a semi going 60 mph and stay behind them as long as I can. Not to hypermile, I don't get that close. Just so they take the "heat" from passing cars. Often a U-haul trailer will be going 60. If I run out of trucks or trailers I go 65. If I'm getting caught in a pincher move I go as fast as **** to get clear of it! I'm sure I've surprised a few people when a Chevy Hatchback is all of a sudden a quarter mile ahead.

I would actually say this is a great idea other than the air quality!

 

[hatchy]

I'll play... Im going to guess 15mph. Based on riding my bicycle and feeling what air does.

But yeah basically whatever high profile truck is in the slow lane, get behind them.50 to 55 if you're lucky enough to find somebody that slow to safely get in to line with.

OOh. The other day I did 4+ behind a big box van going 70mph. True story.

 

[JPT]

The question itself is a bit of an oxymoron. As others have pointed out, the slower you go, the greater your range in nearly all use cases unless it's -20 outside and you're debating if it's better to go 10 MPH or 20 MPH (heating the cabin consumes a sizable amount of energy when it's cold out).

I've run some numbers on the Bolt regarding completing long distance trips as quickly as possible, and assuming there is a DCFC placed exactly where you need it all along your route, the most time efficient speed is 75 MPH. Any faster and you're expending energy faster than you can put it back in at a DCFC. In other words, the time you save by driving above 75 MPH is more than eaten up at the charger.

With cars that can charge at greater than 55 kW, there's practically no limit to the most time efficient speed you can travel. Driving faster will get to the destination faster.

I've read a lot about the best speed to drive to reduce total trip time and I would describe most of the logic as true, but misleading:
-Chargers aren't exactly where you need them.
-The car tapers the charge above 55% so you'd need to mostly use the bottom half of the batery to reach the peak charge speeds so need to stop twice as often.
-There is often a time penalty for deviating from your route to go charge somewhere.
-If the battery is cold the charging will be much slower than expected. Like 15kW instead of 55kW while the heater warms up the battery.
-If it's really cold, you'll be using 7kW just to stay warm. This means that driving fast will make your consumption sky high. It also means that your efficiency will suffer if you drive really slowly.

I'd love to see an analysis that factors this stuff in, especially the cold battery part.

 

[redpoint5]

Too many variables. I'm sure it could be done, but it's very complex.

My calculations were based on a speed vs efficiency chart. It's a single source, so the accuracy is in question.

My calcs also assumed chargers in exactly the spot you needed, with charging occurring at 10% battery, and I forget the charging duration I used. Perhaps 30min to spend little time in the taper.

It ignored environmental factors.

Still, 75 MPH is in the ballpark of speed efficiency in a perfect charging world.

 

[GregBrew]

I'll play... Im going to guess 15mph. Based on riding my bicycle and feeling what air does.

But yeah basically whatever high profile truck is in the slow lane, get behind them.50 to 55 if you're lucky enough to find somebody that slow to safely get in to line with.

OOh. The other day I did 4+ behind a big box van going 70mph. True story.

When delivering my son's '87 Jeep Wrangler from HB, CA to Hineville, GA a few years ago, I wasn't in any hurry. I quickly learned to tuck behind (not drafting) Swift-branded semi's on I-40 all the way across. Swift truck drivers must have strict over-speed penalties, because they were all essentially stuck at 55mph, which was fine for me. Wind noise in a bikini-topped Wrangler (even with door skins and a back drape) is hellacious at anything over 55, and I wanted to enjoy my music without being "blamed" for going too slow on the highway. The speeds of other-branded semi rigs was all over the map.

 

[KeithMoon]

I'll play... Im going to guess 15mph. Based on riding my bicycle and feeling what air does.

But yeah basically whatever high profile truck is in the slow lane, get behind them.50 to 55 if you're lucky enough to find somebody that slow to safely get in to line with.

OOh. The other day I did 4+ behind a big box van going 70mph. True story.

When delivering my son's '87 Jeep Wrangler from HB, CA to Hineville, GA a few years ago, I wasn't in any hurry. I quickly learned to tuck behind (not drafting) Swift-branded semi's on I-40 all the way across. Swift truck drivers must have strict over-speed penalties, because they were all essentially stuck at 55mph, which was fine for me. Wind noise in a bikini-topped Wrangler (even with door skins and a back drape) is hellacious at anything over 55, and I wanted to enjoy my music without being "blamed" for going too slow on the highway. The speeds of other-branded semi rigs was all over the map.

You might be the only person on Earth to have gotten over 15mpg in a Jeep ?

 

[redpoint5]

I averaged 18 MPG and went as high s 20 in a Jeep Liberty. Now, you can debate that it's not a real Jeep, but it did have low range. It would kick into an overdrive gear at 60 MPH.