Posts: 2
Joined: Tue Jan 28, 2020 11:53 pm

4+ mile / KWh advice

Thu Jan 30, 2020 11:39 am


I recently purchased a CPO Spark EV with 44,000 miles. This is my second Spark EV as I leased a 2014 when it first came out. I love the car and it would be my perfect car if it only had a 150 miles range or so. That said, the range is what it is. I understand that battery degradation is an unavoidable consequence of having an EV.

As I understand it the battery capacity of 2015 -2016 Spark EVs is 19 KWh and the EPA estimated range is still 82 miles. If all of the battery capacity were useable (which I know it isn't) that would mean that under EPA conditions 4.3 mi/KWh would be the energy efficiency. If one assumes a useable capacity of 18 KWh then we are talking about 4.6 mi/KWh. Battery degradation and reduced capacity would obviously reduce overall range, but it should reduce efficiency on a mile / KWh basis. Unless there is an increase in driveline inefficiency the "mi/KWh" numbers should remain constant, no?

Over my first 250 miles I am seeing efficiencies in the 3.9 - 4.0 range when I charge and reset, and average battery capacity of 13.23 KWh (70% of new). (driving in "L" which would over represent capacity due to Re-gen). even when I drive at a leisurely pace, 60 mph on the highway, I only see 4.0 mi/KWh. My tires look to be pretty crappy generic unbranded "Road Huggers". I seem to remember on my 2014 Spark EV being able to readily achieve 4.5 - 5.0 mi/KWh efficiencies on the stock Bridgestone Ecopia tires and even when I changed the fronts to Yokohama Avid Ascends, efficiencies barely dropped.

Would simply going with a better or LRR tire improve my efficiencies? Have other owners seen a drop in mi/KWh independent of other changes?


Posts: 2
Joined: Fri Jan 31, 2020 3:23 am

Re: 4+ mile / KWh advice

Fri Jan 31, 2020 3:29 am

As you've owned one before, I'm sure you're aware that cold weather has a huge effect on battery performance.

I don't know exactly how much effect LRR tires have (mine came with regular tires on the front), but I can't imagine Chevy would have chosen to use such crappy performing tires if they didn't help substantially.

Posts: 1277
Joined: Fri May 01, 2015 5:52 am
Location: KC,MO

Re: 4+ mile / KWh advice

Fri Jan 31, 2020 4:32 am

Slowing the car, and getting the Regen power from that, is exactly the same using L or using the brake pedal in D.
GM has Blended Brakes. Not all EV's have that tech. Brand T definitely doesn't....

You should put a dollar/penny amount on chasing a higher mi/kWh number.
Same with swapping your current tires for LRR tires.

As you know, just drive slower if you want to save a few pennies.
Used '14 2LT w/ DCFC. +78 K miles.
Mostly free charging! Only one LONG visit to the shop....
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 1st try car died again, 2nd try not covered / cost $800. 3rd try fixed the problem.

Posts: 2
Joined: Tue Jan 28, 2020 11:53 pm

Re: 4+ mile / KWh advice

Fri Jan 31, 2020 7:40 am

Thanks for the feedback guys.

It's not a financial or even speed concern. I love this car so much I got it even though I have a twice a week of 120 miles one way commute. and a once a week round trip commute of 50 miles over a mountain pass. fortunately there are DC Fast charge stations every 30-40 miles along my route 120 mile route, but I would like to find a way to only have to fast charge once per trip and still drive faster than 55 (with a 10 mile range buffer). Also hilly miles sap more power than flat miles regardless of speed, so I need even more buffer on my last ascent to be able to make it over the pass.

If I can get 4.5-5.0 mi/KWh my distances wouldn't necessitate a change in driving.


Posts: 108
Joined: Mon Feb 04, 2019 10:47 am

Re: 4+ mile / KWh advice

Fri Jan 31, 2020 9:07 am

I have aftermarket front tires so can't speak to the decline due to tires but I do keep my tires at the maximum cold PSI stated on the sidewall of the tire. I would try not to use any heat or air just the seat heaters intermittently if you must. Safely draft larger vehicles. Turn off the head lights during the day if you feel safe and are seen without them, it's not a huge load but over 120 miles it could add up. On days in the 50's with cooperative traffic lights and with max speeds never over 40mph I can get 5-7mi/kWh but highway speeds are a different ball game and you may not be able to improve much past what you have already.
2016 Spark EV
2017 Volt

Posts: 1
Joined: Wed Feb 19, 2020 8:38 pm

Re: 4+ mile / KWh advice

Wed Feb 19, 2020 8:49 pm

LRR tires make a huge improvement. I’m averaging an ok 3.5 mi/kWh, I say ok because I had to swap my LRR’s for heavy snow tires, plus cold temps here in Pittsburgh.

In the summer/fall I was easily averaging 5+mi/kWh.

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