As a battery's state of charge (SOC) decreases, an EV's acceleration times increase, but it varies by make and model.
We took three EVs to the track to test how their 60-mph times change at different SOC increments.
Among the Hyundai Ioniq 5, Lucid Air, and Rivian R1T we tested, only the Hyundai's 60-mph time was unaffected until its SOC dropped below 20 percent.

Welcome to Car and Driver's Testing Hub, where we zoom in on the test numbers. We've been pushing vehicles to their limits since 1956 to provide objective data to bolster our subjective impressions (you can see how we test here).

Pretend for a moment you're testing a 668-hp Cadillac CT5-V Blackwing with a full 17.4-gallon tank of gas. As you do more and more acceleration runs, fuel burns off, making the car lighter and thus slightly quicker. An EV, however, doesn't lose weight as it consumes energy.

Electric cars' acceleration times increase as the battery's state of charge (SOC) drops. But some OEMs are better than others at managing this performance slip, so we decided to take three EVs to the track and clock their 60-mph times with a fully charged pack, with 10 percent charge, and at several increments in between. The acceleration degradation we measured isn't necessarily representative of all EVs, but it provides a good picture of how 60-mph times increase as the battery discharges.

Hyundai Ioniq 5, Lucid Air, Rivian R1T collage

The test revealed that the 430-hp Lucid Air and the 835-hp Rivian R1T start losing performance immediately. But the Hyundai Ioniq 5 remains consistent until its SOC drops below 20 percent. The Hyundai has a few things working for it. First, making 320 horses generates a fraction of the heat that 835 does, so the battery isn't fighting excessive power-robbing temperatures immediately. Plus, the battery can make 365 horsepower, but the 5's motors request 320 at most, resulting in an EV that can deliver its maximum thrust over the widest SOC range we've measured.

State of Charge - Rivian R1T charging graphic

2022 Rivian R1T Quad-Motor

Motors: 4 AC | Horsepower: 835 hp | Torque: 908 lb-ftBattery Pack: 128.9 kWh lithium-ionCurb Weight: 7054 lb

Fully charged, the R1T hit 60 mph 1.3 seconds quicker than the Ioniq 5 and 1.2 seconds quicker than the Air. That's expected, given the performance upgrade. However, the champion at the start would eventually fall into last place once the battery percentage was low enough, or in this case, at 10 percent.

State of Charge - Hyundai Ioniq 5 charging graphic

2024 Lucid Air Pure RWD

Motor: 1 AC | Horsepower: 430 hp | Torque: 406 lb-ft

Battery Pack: 88.0 kWh lithium-ionCurb Weight: 4652 lb

Once the Air drops below a 22 percent state of charge, it cuts its top speed from 127 mph to 92 mph to reduce energy consumption. The only single-motor EV in the test, the Air's acceleration only dropped by 0.3 sec after consuming 60 percent of its battery. A bigger loss of power was detected at the 20 percent mark, where the acceleration to 60 mph slowed to 4.9 seconds.

State of Charge - Lucid Air charging graphic

2023 Hyundai Ioniq 5 SEL AWD

Motors: 2 AC | Horsepower: 320 hp | Torque: 446 lb-ft

Battery Pack: 77.4 kWh lithium-ionCurb Weight: 4547 lb

At a 5 percent charge, the Ioniq 5 was 1.7 seconds quicker than the R1T. With a triple-dog dare on the line, we had to see whether the Ioniq 5 ever limited its top speed. It didn't. Even with 1 percent charge, the Hyundai will go 117 mph.

This article originally appeared in the May/June issue of Car and Driver.