Can you point me to some info/chart on "mpg" vs speed for EVs?

[jim04g]

Was curious about "mpg" or watts-used or recharge-time or whatever the preferred measure is for EVs, vs road speed.
Perhaps my web-search terms are inadequate, but could only find ICE charts which may have been created back in the 1970s' National Maximum Speed Limit era.

 

[ecotourist]

I don't have a chart but I do have an observation. The energy usage of my Tesla Model 3 drops off quite a bit above 100 Km/hr (62 MPH).

On a long trip, you and the Nav system sketch out the charging plan for the day. Then the Tesla constantly adjusts its prediction of the remaining charge upon arrival at the next planned Supercharger. If the remaining charge starts looking a bit thin, you just slow down and the predicted charge quickly improves.

I suppose the same drop off happens with a gasoline engine, you're just not aware of it.

 

[UncleDave]

I suppose the same drop off happens with a gasoline engine, you're just not aware of it.

It does, but to visualize it you need to reset the average after the speed change.

Most poeple dont reset their average MPG /range meter at the new speed so it remains computed on the whole tank (or since last reset).

 

[Jetronic]

Was curious about "mpg" or watts-used or recharge-time or whatever the preferred measure is for EVs, vs road speed.
Perhaps my web-search terms are inadequate, but could only find ICE charts which may have been created back in the 1970s' National Maximum Speed Limit era.
View attachment 118913

For an EV they start high at low speeds and continue to go down as you drive faster. If you flip the chart left to righ then 5 mph would be where 60 is now and 75 where 5 is now. Give or take. The dropoff at high speed is less for more slick and smaller frontal area cars vs the opposite.

 

[Jetronic]

It does, but to visualize it you need to reset the average after the speed change.

Most poeple dont reset their average MPG /range meter at the new speed so it remains computed on the whole tank (or since last reset).

The range drops quickly if I drive faster (seconds to a minute) but if I reduce speed it takes a while to increase range significantly... for every mile travelled slower it might report an increase of 2 miles range. I'm not unhappy about that, I'd rather underestimate the range than end up without fuel where there's none to be had.

 

[BMWTurboDzl]

It's vehicle dependent because all vehicles have different drag coefficients. You'll then have to a lot of calculations.

Most Aerodynamic Electric Cars | EVspecs

Most Aerodynamic Electric Cars

www.myevreview.com

 

[atikovi]

Add towing a trailer to the mix and range drops like a rock.

 

[PimTac]

It will vary depending on the vehicle and the driver. Nothing is that exact.

 

[JohnnyG]

Regardless of drag coefficient, the faster you go, the more wind resistance, hence more electricity usage.

 

[UncleDave]

Was curious about "mpg" or watts-used or recharge-time or whatever the preferred measure is for EVs, vs road speed.
Perhaps my web-search terms are inadequate, but could only find ICE charts which may have been created back in the 1970s' National Maximum Speed Limit era.
View attachment 118913

some good data here.

Tesla Model 3 Performance vs RWD consumption - Real Driving Data from 233 Cars

As you may already know, ABetterRouteplanner.com collects driving data from contributing users. This data is used to improve the ABRP car models (i.e. the mathematical representation of each type of car) and also, to give back to the ABRP community providing the data, to be published here in the ...

forum.abetterrouteplanner.com

 

[jim04g]

Very much appreciate both the links, and the personal observations. Always something new to learn.
Quickly eyeballing the Tesla plots, it might look like the max speed still within the flatter part of the efficiency curve is not too different from that for ICE, such as implied in the posts discussing resistance to motion above.
- OP

 

[Cujet]

Maybe what you are looking for is the "Watt hours per mile" (or Km) chart. Clearly, the most efficient speed for these EV's hovers around 25 to 32MPH.

NOTE: These numbers are LOW. That is the power going into the motor. Not the amount the Electric Meter counts to go that distance. Remember, there are losses in the charger, charging and discharging and in the controller. The electricity purchased does not match what goes into the motor.

Here is a graph of consumed power (Watts into the motor) vs. speed. Clearly the power used at 80 mph (128Kph) is about seven times as much as at 20 mph (32Kph). Yet you are going not quite 4x as fast.

Some conversions:

• 90 kph / 181 Wh/km ~= 56 mph / 290 Wh/mi
• 100 kph / 192 Wh/km ~= 62 mph / 307 Wh/mi
• 110 kph / 207 Wh/km ~= 69 mph / 331 Wh/mi
• 120 kph / 229 Wh/km ~= 75 mph / 366 Wh/mi

 

[PandaBear]

Was curious about "mpg" or watts-used or recharge-time or whatever the preferred measure is for EVs, vs road speed.
Perhaps my web-search terms are inadequate, but could only find ICE charts which may have been created back in the 1970s' National Maximum Speed Limit era.
View attachment 118913

The energy used portion of EV is probably identical to a hybrid, other than some aerodynamics improvement for a smaller front grill. The mpg can be measured on a dyno.

The mpg/mph graph of an EV / hybrid should be very high at low speed and very low at high speed, due to not having a powerband for a gasoline engine. It should be proportional to the aerodynamic drag.

 

[Cujet]

The energy used portion of EV is probably identical to a hybrid, other than some aerodynamics improvement for a smaller front grill. The mpg can be measured on a dyno.

The mpg/mph graph of an EV / hybrid should be very high at low speed and very low at high speed, due to not having a powerband for a gasoline engine. It should be proportional to the aerodynamic drag.

That is an interesting thought. It could very well be that overall energy consumption graphs match well.

 

[CR94]

... The mpg/mph graph of an EV / hybrid should be very high at low speed and very low at high speed, due to not having a powerband for a gasoline engine. It should be proportional to the aerodynamic drag.

A graph of energy consumed per unit distance by an EV over a range of speeds will more closely parallel energy required to overcome aerodynamic and other drag than a corresponding graph for an engine-powered vehicle. That's because engines are very inefficient at low power output corresponding to low speed.

No clue what you mean by engines "not having a powerband."

 

[JeffKeryk]

A graph of energy consumed per unit distance by an EV over a range of speeds will more closely parallel energy required to overcome aerodynamic and other drag than a corresponding graph for an engine-powered vehicle. That's because engines are very inefficient at low power output corresponding to low speed.

No clue what you mean by engines "not having a powerband."

"Not having a powerband" refers to electric motors vs internal combustion engines torque curve. The motor has a very flat, off idle torque curve vs the RPM dependent curve if the ICE engine. This is why most EVs do not have a traditional, multi gear transmission. They don't need it.

It is also why they are so quick; no up shifting and no trans lag.

 

[CR94]

"Not having a powerband" refers to electric motors vs internal combustion engines torque curve. The motor has a very flat, off idle torque curve vs the RPM dependent curve if the ICE engine. ...

That depends very much on your assumptions and the type of motor in question. Granted, the motors typically used to power vehicles can be controlled to behave that way, not just "off-idle" (? whatever that is for an electric motor), but from zero speed. Even they can be more efficient with alternate ratio(s) of motor speed to wheel speed.

Check out torque vs. speed curves for simple conventional brushed DC or shaded-pole motors.