An overlooked factor in evaluating EVs (battery and plug-in hybrids) is their energy efficiency. We are used to evaluating internal combustion engine-driven (ICE) vehicles in terms of MPG (miles-per-gallon). The analog for EVs would be miles-per-kWh -- how far will they go on a kWh of energy. (Sometimes car vendors publish the reciprocal Watt-hours-per-mile for various driving conditions (city, highway, combined), but these numbers are not consistently available.*)
I've charted the miles-per-kWh for many of the current or soon-to-be-available battery-driven EVs and PHEVs (plug-in hybrid EVs). For the PHEVs I'm only looking at the battery-driven mode, which is often the default mode of operation. Miles-per-kWh is simply calculated by EPA range miles divided by battery capacity.
Why are there such differences?
vehicle
|
battery
|
range
|
efficiency
|
weight
|
power
|
kWh
|
(EPA) mi
|
mi/kWh
|
lbs
|
hp
|
|
Hyundai IONIQ EV
|
28
|
124
|
4.43
|
3164
|
118
|
Tesla 3 Long Range
RWD
|
80.5
|
325
|
4.04
|
3627
|
258
|
Hyundai Kona
Electric
|
64
|
258
|
4.03
|
3715
|
201
|
Tesla 3 Std Range
Plus
|
60
|
240
|
4.00
|
3627
|
258
|
Chevy Bolt EV
|
60
|
238
|
3.97
|
3550
|
200
|
Nissan Leaf e+
|
62
|
226
|
3.65
|
3500
|
214
|
Tesla S Std Range
|
75
|
285
|
3.80
|
4769
|
417
|
Kia Nero EV
|
64
|
239
|
3.73
|
3854
|
201
|
Tesla S Long Range
|
100
|
370
|
3.70
|
4883
|
417
|
Tesla X Std Range
|
75
|
250
|
3.33
|
5307
|
417
|
Hyundai IONIQ PHEV
(battery)
|
8.9
|
29
|
3.26
|
3070
|
139
|
Tesla X Long Range
|
100
|
325
|
3.25
|
5421
|
417
|
Kia Nero PHEV
(battery)
|
8.9
|
26
|
2.92
|
3161
|
139
|
Toyota Prius Prime
(battery)
|
8.8
|
25
|
2.84
|
3365
|
121
|
Jaguar I-Pace
|
90
|
234
|
2.60
|
4920
|
394
|
Audi e-tron
|
95
|
204
|
2.15
|
5490
|
224+184
|
Subaru Hybrid
Crosstrek (battery)
|
8.8
|
17
|
1.93
|
3700
|
148
|
The poor efficiency of PHEVs compared to many battery EVs may be because in battery-only mode the vehicle is only using the electric motor power plant that is just one part of the two complementary power plants in the car. PHEVs have an ICE power plant and an electric power plant. (Note: some electric power plants consist of more than one electric motor.)
But why are the Jaguar and Audi all electric vehicles so inefficient? It's not just horsepower or curb weight. Tesla has models with comparable curb weight and power but with much better efficiency.
My guess is that because the I-Pace and e-tron are first efforts for Jaguar and Audi respectively efficiency was not the most important design criteria for either company. Performance and range were probably prioritized over efficiency in these high-cost high-performance vehicles. (It is probably easier to get more range by hauling more battery weight than to make a vehicle faster or better handling.)
But huge batteries have other design costs. Consumer Reports has criticized the Tesla models and Jaguar I-Pace for long charging times. They measured 13 hours to charge the I-Pace on a 240 V-AC home charger. Telsa 100 kWh batteries charge in about 12 hours through 240 V-AC. The 95 kWh e-tron battery can charge in 9 hours at 240 V-AC. Faster charging for all these models is sometimes available through public DC fast charging stations.
It will be interesting to see how Mercedes, Porsche and VW address efficiency with their anticipated EV models.
*Update: FuelEconomy.gov After publishing this post, I came across this website published by the EPA with comparable fuel efficiency statistics for every vehicle sold in the US. https://www.fueleconomy.gov/feg/Find.do?action=sbsSelect