Electric vehicles don’t lose power like combustion cars do when driven at high altitudes, but driving up a mountain pass will make their range disappear much quicker than normal. An EV consumes significantly more energy when climbing a gradient than on level ground, but if you follow the climb with a long descent with lots of brake regeneration, you should recover many of the lost miles.
That’s exactly what TFLEV’s Loveland Trials EV test can reveal. It involves driving from Boulder, Colorado, to the top of Loveland Pass, which peaks at an elevation of 11,990 feet, and going back down the same way. Driving on the same road both on the ascent and the descent is the only way to have some semblance of accuracy when comparing the amount of energy spent going up with what is recovered through regeneration on the way down.
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Driving EVs through the mountains is both easier and harder
The fact that EVs don't lose power at high altitudes (some even seem a bit quicker with the thinner air) makes them perfect for a mountain road drive. However, when climbing through a steep mountain pass, electricity consumption will be much higher than usual, so you need to plan ahead to make sure you won't become stranded. You can, of course, rely on brake regeneration to replenish range if there's a significant downhill section to your mountain drive.
In this video, they used a 2024 Hyundai Ioniq 5 with the 77.5 kilowatt-hour Extended Range battery pack, which bumps up the range from the standard 58 kWh pack’s 220 miles to 260 miles. When they set off, the state of charge is 99%, and the car shows 256 miles of range, which is almost bang on with the official EPA estimate.
When going through a mountain pass, you can also expect temperature changes regardless of the season. This becomes more important if you plan on stopping at some point, because if it suddenly gets really cold, you may lose more range than you think, even if you just leave the car parked.
Electric vehicle batteries have an ideal operating temperature window where they can provide the maximum range, and if you have outside temperature extremes, the car will expend energy to keep the cells happy.
The reviewers in the TFLEV video tackled the mountain pass in summer when sudden temperature changes are not as likely, and by the time they reached the highest point on the road (when they stopped and turned around), they covered 74.1 miles and the range prediction said 138 miles. So the car lost 118 miles of predicted range in 74.1 miles, specifically because of the climb, with an average efficiency of 2.2 miles per kWh, which is way higher than what the car gets on mostly level roads.
On the way down, the predicted range starts to climb as the efficiency starts increasing because of the plentiful electrons being gained from regen. By the end of the almost 149-mile trip, efficiency had gone up to 3.7 miles per kWh, and the car still had 46% left in its battery.
It’s worth noting that when on the descent part of the mountain pass trip, you should make sure the vehicle has brake regeneration enabled. Most EVs allow you to adjust the level of regen, and in some, you can even coast (which can be more efficient on flat ground). If you coast and ride the friction brakes on the entire descent, you may not only start to experience brake fade due to the rotors overheating, which can be dangerous, but you also won’t get back any range.
The Hyundai Ioniq 5 has several regen modes including one that’s called i-Pedal, which allows you to drive the car only by using the accelerator pedal. With i-Pedal engaged, you won’t have to touch the brake pedal on your mountain pass descent unless you need to scrub off a lot of speed for a tight hairpin or if a bear sprints across the road and you need to perform an emergency stop.
You can also constantly adjust regen, which you can do in most electric cars, Ioniq 5 included, via paddles behind the steering wheel. You will decrease regen where it’s safe to pick up more speed and increase it as you approach a corner. Some manufacturers, like BMW, don’t allow you to adjust regen in the latest EVs like the i5 Touring that we recently tried. These cars use an adaptive regen system so it’s done automatically based on what kind of turn is coming up and whether there’s another car or an obstacle in front of the car.
