R2 highway efficiency (~3mi/kWh) is better than in the city (~2.5mi/kWh)

[dcdttu]

I was close after he ignored me, but I like to think I have thicker skin than someone that went right for insulting my apperance.

I don't know what he insulted about you, but your goatee situation is epic and he can shut it.

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[VandalSibs]

I don't know what he insulted about you, but your goatee situation is epic and he can shut it.

I'm only guessing it was that. But how he responded to me by including a screenshot of my profile pic, it's a pretty decent guess to make.

 

[Lionel_Hutz]

I really doubt this is a motor or battery temperature issue. It's not winter, and the motors don't really care if they're ambient temp or not.

I would be more curious to know if these are a lot of short errand trips from the perspective of HVAC load. It was extremely hot in CA last week, so multiple short trips could be connected with max A/C usage to get the cabin down to temperature.

 

[rvnxyz001]

R2 gets bad efficiency at 80 mph: "Well, EPA doesn’t test at 80 mph"

R2 gets ~2 mi/kWh at low speed: "Well, EPA doesn’t test that slow either"

Apparently EPA tests the R2 at one very specific magical speed where it suddenly becomes efficient. We just haven’t found it yet

 

[Redmond Chad]

A few have already noted that short trips can be very inefficient. Below are some numbers from a gas car that might help illustrate that.

My last gas car was a 2005 Honda Insight. I got an overall average of 62mpg in it. I didn't drive it on the freeway much, but that average included some longer, steady-speed backroad drives where I got up to 82mpg round trip (up to 104 one-way).

On my 4-mile trip to work in winter, I got 44mpg. Then I added a block heater, and it went up to 55mpg. (The block heater used enough electricity that I wasn't really saving energy or money; but I did at least switch some gas use to electricity use).

Part of the issue is that motors and batteries are less efficient until warmed up (true that electric motors don't lose nearly as much as gas ones do; but cold EV batteries can be quite a bit less efficient when cold; how much depends on chemistry and pack management); part is the initial HVAC load.

In some EVs the same system that warms/cools the cabin also does the same job for the batteries; in one rough measurement on an EV years ago, it looked to me like about 2/3 of the HVAC system energy went to the batteries and 1/3 to the cabin.

 

[Redmond Chad]

R2 gets ~2 mi/kWh at low speed: "Well, EPA doesn’t test that slow either"

I remember years ago some Tesla owners getting their cars back from service appointments and being shocked at the recent efficiency graph...they assumed the technicians had taken their cars for a joyride. When your metric is mi/kWh, and you don't drive many miles so you have a small numerator, things other than driving that use energy drive up the denominator and can lower the efficiency a great deal.

When I first got my R2, it showed an efficiency of 0.67 mi/kWh. It only had 20 miles on it, but had apparently been left turned on for 89 hours with HVAC running.

 

[Zathras]

If you're doing just quick little trips in the city without some sustained driving (5+ miles), then the motors and battery will have not warmed up a lot (outside of summer of course). So for example, my three mile commute to work isn't as efficient because of this. Granted for me it's compensated for as my drive to work is mostly downhill...

That's really interesting. Now, how do I warm it up while sitting in the driveway? LOL.

Actually, I guess I need to avoid short drives? Being retired, I am able to go wherever I want whenever I want. And considering my current car I bought in September 2019 (less than six months before retirement and the arrival of Covid (March 9th)) it still only has 23,000 miles. I'm gonna have to up my game. California is a good place to have this issue.

 

[evilyn]

A few have already noted that short trips can be very inefficient. Below are some numbers from a gas car that might help illustrate that.

My last gas car was a 2005 Honda Insight. I got an overall average of 62mpg in it. I didn't drive it on the freeway much, but that average included some longer, steady-speed backroad drives where I got up to 82mpg round trip (up to 104 one-way).

On my 4-mile trip to work in winter, I got 44mpg. Then I added a block heater, and it went up to 54mpg. (The block heater used enough electricity that I wasn't really saving energy or money; but I did at least switch some gas use to electricity use).

Part of the issue is that motors and batteries are less efficient until warmed up (true that electric motors don't lose nearly as much as gas ones do; but cold EV batteries can be quite a bit less efficient when cold; how much depends on chemistry); part is the initial HVAC load (and in some EVs the same system that warms/cools the cabin also does the same job for the batteries; in one rough measurement on an EV years ago, it looked to me like about 2/3 of the HVAC system energy went to the batteries and 1/3 to the cabin).

I fully confess that my driving style is not exactly of the patient kind. And the R2 makes it way too much fun to leave everybody behind.
The last ICE vehicle I owned was a Honda Pilot 4WD, which was barely getting 14–15 mpg in city driving. It was a fun vehicle, but I always had to remind myself about gas prices. With the R2, you can have all the fun without the guilt.
And don't take my numbers as an efficiency test. I was simply curious to see what numbers I'd get with my regular, everyday driving. That's why I chuckled when I noticed that, in one particular way, the R2 was reminding me of an ICE vehicle, my city efficiency was actually worse than my highway efficiency.
I'm sure my driving style has a tiny bit to do with it.

 

[mkhuffman]

...
Actually, I guess I need to avoid short drives? ...

If you can charge at home, the efficiency of local drives is irrelevant. You just plug it in every night and it is always ready to go the next morning.

The highway efficiency discussion is really about range and needing to find a public charging option. Longer highway range means greater flexibility regarding where you stop.

 

[CharonPDX]

In city driving, you also have more of the "vampire" losses. If you have a tungsten foot, and it's hot where you are so you're running the AC full blast, those two combined will add up to quite a bit more energy loss in the city than "expected".

 

[DanielEV2023]

Noticed this as well with collected data. I thought it was some data error and was very surprised. Also thought city driving was supposed to be more efficient.

Is this how all EVs work?

Not sure what this is measuring. Is this at a steady speed or average speed? Ambient temperature matter greatly to EV's but temperature is not stated here. Air resistance increases with the square of velocity. Electric motors have close to the same efficiency across a wide power levels. So, all other things being equal, EV's will achieve peak efficiency at about 28 mph. If regen is designed well, around town driving can be up to 2x more efficient than high speed (>75mph) highway driving.

 

[rvnxyz001]

Not sure what this is measuring. Is this at a steady speed or average speed? Ambient temperature matter greatly to EV's but temperature is not stated here. Air resistance increases with the square of velocity. Electric motors have close to the same efficiency across a wide power levels. So, all other things being equal, EV's will achieve peak efficiency at about 28 mph. If regen is designed well, around town driving can be up to 2x more efficient than high speed (>75mph) highway driving.

The chart mixes a few different things. The 50/60/70/80 mph points are controlled or near steady-speed tests, while some of the others are owner trips using average speed...

Temperature, wind, elevation, traffic, tires and drive mode obviously matter too, and I track those when the source gives them. I just didn't put all of that on the chart because it would get messy fast.

I also don't have enough comparable temperature data yet to show a meaningful "temperature vs range" curve. The tests where temperature is known also differ in speed, route, wind, elevation, tires, traffic, etc., so it would be pretty misleading to pretend temperature alone caused the difference.

And yes, it's obvious that EV efficiency drops as speed goes up. The point of the chart wasn't to prove that, just to show roughly how much the R2 drops based on the data I have: about 3.15 mi/kWh at 60 mph, 2.83-3.06 at 70 mph, and 2.2-2.46 at 80 mph.

 

[Mathme]

When it's hot outside and I'm running several errands, I will turn on Pet mode when "popping into a store really quick" so the cabin stays cooler and the AC can keep up. I'm not sure for 10-15 minutes if this is a help or hinderance, but on a hot day it is nice to get back into a pre-cooled car.

 

[evilyn]

Those are good numbers. I like your perspective on the range & charging.

Your positive post will no doubt spawn another AI-enabled "range" epistle from our resident expert on the topic.

I'm afraid the experts will be disappointed by my unorthodox driving habits.
Was doing city driving for several hours today, but it was a different route, not the usual one -- less traffic, fewer traffic lights. I returned home with 4.33 mi/kWh efficiency this time. So the numbers are all over the place. That will confuse experts for sure.
I'm certain those who like hypermiling will be able to do so and will show us their 400 mile per charge trips.

 

[MaskedRacerX]

It's super easy on shorts trips - especially around town - to do a lot of start/stop, quick little bursts, and like someone else suggested, start with a cold vehicle. Plus a small overall distance so small increases in power use affect the average more.

Our BMX iX around down is generally lower than our sustained 75MPH on the highway over longer distance.

Plus, sport mode, red-light grand prix, etc., etc.

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