S+ Efficiency vs. SV+ Efficiency testing

Ok, this is the first of 2 posts related for side by side testing of our S+ and SV+, both 2019s.

My son is back from college and so had the extra driver to do the tests.

We recently moved the SV+ from the OEM 17" Michelins to 16" CrossClimate2s on the OEM 16" Leaf rims.

The test circuit was a 18.5 mile loop on the interstate, which we did 2x times with each car taking one loop in the lead position.

Speeds were approximately 60mph, but did move around between 55 and 65 due to traffic on the interstate.

The S+ has a SoH of 92.35% and the SV+ 90.56%

Starting metrics.

Ambient 39F with light wind. Neither car used heat/AC or seat/steering wheel heaters. Radio was on for sanity. Fan speed low. 43 psi for both cars.

S+ 419 GIDs 32.5 kWh and a battery temp of 41F.
SV+ 406 gids 31.5 kWh and a battery temp of 52.5F

Ending metrics post 37 miles of driving. Odometer for both was exactly 37.0 miles traveled.

S+ 313 gids 24.3 kWh and a dash reading of 4.7 miles/kWh
SV+ 294 gids 22.8 kWh remaining and a dash efficiency of 4.1 miles/kWh (and clicked to 4.0 just after a photo)

221 watts per mile for the S+ and 251 for the SV+

2.86 gids/mile for the S+
3.03 gids/mile for the SV+.

The .6-.7 difference is pretty significant as it would represent 30+ miles of range difference in the cars on a full drive.

Next step is to flip the tires/rims between the cars and see if the efficiency flips as well.

My hypothesis is that the S+ and S+ will be equal post the change, but will not flip positions.

Will update with the 2nd test post change in a couple weeks.

Yeah, 0.6 to 0.7 is a big difference. You didn't mention the tire pressures, but my guess is CrossClimate2 tires have a lot more grip than the OEM tires from before. I'm driving a 2015 SV (loaner from family while my 2020 is in the repair shop) and before I inflated the tires to nearly max safe cold temperature, I was averaging around 4.2 m/kWh in city driving which is worse than what I get on my 2020 (which is much, much heavier) but once I got the tires inflated up from 33 PSI :lol: to around 48 PSI , was about to raise it up to around 4.5 m/kWh. The sad thing is, my 2013 SV easily got 5.0 m/kWh back in the day on the Ecopia tires, so I had no idea that the tires made that much of a difference. Once I looked up the type of tires they put on the 2015 SV I was driving, come to find out they were "sport" tires, so yeah, they have some awesome grip for corning at high speed, but sacrifice a great deal of range. The family member that loaned it to me didn't even know that LRR tires were a thing until I talked with them about the range sacrifice they have been driving on for years. :lol:

43 psi on Both cars. Good catch.

Okay I love geeking out about test data like this so excuse the tone if this comes off as judgey.

Were both cars charged to similar cell voltage levels?
I doubt it makes a large impact in efficiency but that would remove the power electronics efficiency per voltage as a variable.

I will check the voltages that for the 2nd run. Tires getting switched in a little over a week. Notice that the first test did have a colder battery and 2 passengers in the S+ vs. Sv+...making the 15% efficiency difference even more impressive.

I have to say the cross climate2s do amazing in snow..now that we have a little in the Chicago metro area. Compared to the energy savers, it was night and day in terms of confidence and Control on corners and acceleration in the snow.

Ok, tires flipped and test run.

As a reminder I moved the stock 16" wheels with the Cross Climate2 205 55 16 tires to the S+ and the 16" EV01s with Ecopia 422s to the SV+.

Ambient temp 42F. (Super warm for Jan)

Same double loop procedure with 37 total miles traveled. Both cars showed same distance to the tenth at arrival. Roads were wet.

S+ departing metrics: 29.8kWh 385 gids 42.3F 3.691-3.714 mV range.

SV+ departing metrics: 36.3kWh 468 gids 52.4F 3.822-8.43 mV range

S+ Arriving metrics: 20.5kWh 264 gids 45.6F 3.599-3.567 mV range. Dash 4.2 miles/kWh

SV+ Arriving metrics: 28.8kWh 373 gids 52.4F 3.681-3.691 mV range. Dash 4.9 miles kWh.

This test was a little slower in the last leg due to traffic, and because of the fog we both needed to use some pulsed defrost for safety. The SV+ used AC only defrost, but the S+ used the heat+AC defrost, so may need to credit the S+ a 100-200 watts for the heater use. The battery temp heating also could account for some loss of efficiency.

This is an 18-20% gap now the other way suggesting that the wheels do in fact account for the nearly thr entire efficiency gap. Recall in the first test the S+ bested the SV+ by 15%. Lots of small variables obviously, but given the swing I would say we have directional evidence to support.

My previous assumption of something else impacting the efficiency appears to be wrong.

Science is the practice of proving ourselves wrong, I'm afraid. Don't beat yourself up about it.

Thanks Doug, I always appreciate your reports on the 2 Leafs. I run studded snow tires in the winter (Nokian) and the efficiency is WAY reduced during winter months but some of this is due to the S model heater. In a way I am glad to see that the tires are a part of it as well- it is a choice we make each year and the choice to buy the S model is not reversable! Recent driving is showing about 3 m/kWh, a more than 25% reduction from warm summer driving.....

Particularly in low speed driving where tire drag is a major component, tyre choice matters a lot to final fuel economy.

I used to easily get 5 miles/kWh on OEM Michelin Primacy tyres inflated to 48 psi in the summer on our Bolt, and now am happy to see 4.3 kWh/mile driving on CC2 tyres inflated to 41 psi. In each case no cabin conditioning, and the 'winter' driving was a pleasant 40F ambient so the other temperature effects on oils viscosity and air density were pretty modest.

We are taking the S+ with the cc2 tires to Kansas this month, so should be an interesting 560 or so miles with the reduced efficiency. I will certainly post the trip notes from the journey.

At 32F here in Chicago my SV+ now sees low 5s (miles/kWh) as the seat and steering wheel heater is enough. The steering is a little lighter. My daughter likes the new grip with the cc2 tires on the S+.

Nice work … and thanks for taking the time to both test and post your results. The difference in efficiency with the tire change does not surprise me at all. Perhaps a rolling resistance comparative may show up as a standardized tire spec in our future?

A few others have reported seeing a big drop after swapping in summer performance tires in various internet posts, but not sure they have tested quite as thoroughly as you did here.

We switch to studded winters and pretty much stop looking at efficiency with cabin heat and snow in the mix. That said, the removal of trip stats by Nissan is not making it any easier for folks to see the actual impact of tire choices, weather and driving habits :-(

With 3-4 months experience with the EV01s with Ecopias on my SV+, I now think that the SV+ is actually modestly more efficienct than the S+. This is sans any significant hvac usage. It wasn't a very cold winter so that may add some bias to my observations.

There were signs in the 2 tests we ran with the swapped tires, but not sure what would shift efficiency between the cars. Older stiffer rubber in the tires?

I would love to do a side by side efficiency test with a M3 or MY just to satisfy my curiosity.