Regen is complicated. From what I understand it regains as little as 10% or as much as 80%. Traffic conditions, speed, and driving style matter. Gently applying the brake for a long period captures more than pressing firmly for a short period (assuming you are in a car that has regeneration controlled by brakes, the majority).
You always lose something, which is why many cars default to coasting instead of full one pedal driving. City driving regen where you’re repeatedly accelerating from a stop to speed limit and mostly slowing for cars in front or street lights, is different from long trip driving, where you’re interested in the expenditure of excess energy caused by elevation gain and how much of that is recovered on the downhill.
Downhill trips are some of the most efficient. Gentle regen for long stretches. I have some data from skiing trips that suggests my downhill regen is about 75% on my iX. Up the canyon 30 miles, ski a few hours, down the canyon.
Granted this is napkin math and getting into the weeds, but here is one such trip, a 30 miles per kWh leg where I used 22kwh going up and 5.1 coming home, and the car averaged 2.4 miles per kWh on a regular trip the same day.
The uphill/downhill overall cost me about 2.1kwh more than if it had been level. Thats not a wash but not terrible. The thing is that for most long trips you don’t start and end at the same elevation unless you include the round trip done later.
Math seems relatively close since the battery percentage went up by 6 and something % on the way down the canyon on a 111kwh battery, though if I work it out based on that it could be as low as 65% efficiency.
You always lose something, which is why many cars default to coasting instead of full one pedal driving. City driving regen where you’re repeatedly accelerating from a stop to speed limit and mostly slowing for cars in front or street lights, is different from long trip driving, where you’re interested in the expenditure of excess energy caused by elevation gain and how much of that is recovered on the downhill.
Downhill trips are some of the most efficient. Gentle regen for long stretches. I have some data from skiing trips that suggests my downhill regen is about 75% on my iX. Up the canyon 30 miles, ski a few hours, down the canyon.
Granted this is napkin math and getting into the weeds, but here is one such trip, a 30 miles per kWh leg where I used 22kwh going up and 5.1 coming home, and the car averaged 2.4 miles per kWh on a regular trip the same day.
The uphill/downhill overall cost me about 2.1kwh more than if it had been level. Thats not a wash but not terrible. The thing is that for most long trips you don’t start and end at the same elevation unless you include the round trip done later.
| Value | Estimate |
|---|---|
| Uphill energy total | 22.0 kWh |
| Uphill flat-ground equivalent | ~12.5 kWh |
| Elevation energy cost | ~9.5 kWh |
| Downhill trip used | 5.1 kWh |
| Downhill flat-ground equivalent | ~12.5 kWh |
| Energy recovered via regen | ~7.4 kWh |
| Regen efficiency | ~78% |
Math seems relatively close since the battery percentage went up by 6 and something % on the way down the canyon on a 111kwh battery, though if I work it out based on that it could be as low as 65% efficiency.
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