2023 Toyota Prius Prime Falls Short of Its Electric Range Estimate

• The Prius Prime fell short of its EPA-estimated 39 miles of electric-only range — twice.
• At 33.7 miles, the Prius Prime's electric range is very close to what we observed in the Kia Niro PHEV (31.8 and 32 miles) in real-world testing.
• The Toyota delivers a more satisfying driving experience thanks to its much more powerful electric motor, but it's much less practical than the Niro.

Toyota has given the Prius Prime an extreme makeover that makes its predecessor's frumpy styling a distant memory. Plus, this new generation is the beneficiary of a serious cabin upgrade and a big boost of power to its electric motor. The Niro PHEV's changes are less dramatic but still important, and they give the crossover-like hatchback added electric range, technology and practicality of its own. Despite their differing approaches, both vehicles ended up with identical Edmunds ratings: 8.1 out of 10.

Importantly, over the course of our testing, an area in which we thought the Toyota would enjoy a massive advantage became a much closer call: electric-only range. As part of this comparison, we put them to the test.

Always verify the estimates

On paper, the Prius Prime promises a significant advantage in electric range over the Niro PHEV. According to EPA estimates, the Prius Prime offers up to 44 miles of electric range on its base SE trim, while bigger-tired XSE and XSE Touring models offer 39 miles. (Our tester was an XSE.)

In contrast, the Niro PHEV is rated significantly lower: 33 miles for the EX and 32 miles for SX models like our top-shelf SX Touring. That's about 25% less range than the Toyota promises. No surprise, those figures are mirrored by these vehicles' battery sizes: The Prime has a 13.6-kWh pack while the Niro's measures 11.1 kWh.

But when we put both vehicles on our Edmunds testing route to check their real-world range, our results were much closer. The Niro PHEV covered 31.8 miles purely on electrons, coming in just a hair under its official estimate, while our Prius Prime XSE turned in a disappointing 33.7 miles, missing its EPA bogey by a good amount.

This result prompted a personal theory as to why the Prius Prime may have missed its mark, and it has to do with how each vehicle uses its battery pack. While in EV mode, you can floor the Prius Prime's accelerator and the 2.0-liter four-cylinder engine won't even turn on. Its 161-hp electric motor is plenty powerful, offering enough oomph to drive around the city and even get on the highway without any need to awaken the gas engine. All-in, the Prime's hybrid powertrain is good for 220 horsepower.

In contrast, at 83 horsepower, the Niro PHEV's electric motor is roughly half as powerful as the Prime's, and the Kia's total system horsepower is listed at 180. Even when set in its dedicated EV drive mode, if you attempt hard acceleration, the car's programming will quickly turn on the 1.6-liter four-cylinder engine. In order to keep the Kia's engine off and complete the EV portion of our testing loop, we had to to use a significant amount of throttle dexterity that the Toyota didn't require.

Try, try again

I devised a second test to prove my theory. I started by grabbing Reese Counts, a member of our testing team who has an equally curious mind. We set out in these two cars again, but this time, we ran our vehicles simultaneously, with the Prime chasing the Niro at the exact-same pace, encountering the same weather and traffic conditions. My thought was that driving the Prius Prime a bit more gingerly behind the Niro PHEV would help its efficiency greatly, enabling it to put up a better result.

We also ran both vehicles in Eco mode with their climate controls set low and regenerative braking at their maximums to give both cars the chance to put up their best numbers. The Niro PHEV improved slightly, registering 32.0 miles and the Prius Prime netted an identical 33.7 miles. Rats.

Well, that didn't work

Even though the Toyota didn't end up putting up the range figure we had been promised, it's still more satisfying to drive than the Kia by a large margin. The car's new electric motor makes 40 more hp than the last Prius Prime's powertrain did in total, completely transforming the driving experience. The Prime feels like an electric vehicle at low speeds, while the Niro PHEV drives like a hybrid that's just been upgraded in the battery department.

Our team of experts also assessed how long it would take both vehicles to go from 0 to 60 mph using just electric power at the Edmunds test track. The Prius Prime did the deed in 10.8 seconds, but it took the Niro PHEV a slow-motion-worthy 23.4 seconds. In fact, it nearly ran out of space on our straightaway getting up to speed. Of course, nobody will drive this way normally, but it's illustrative of how much more flexible the Prius' powertrain is.

But even though the Prius Prime is quicker and drives better, if electric range is a deciding factor for you, the gap between these two is pretty small in the real world. Furthermore, the Niro PHEV's bigger cabin, simpler tech and much larger maximum cargo space might actually sway buyers toward the Kia. To see how these PHEV heroes compared in other areas, be sure to check out our video above.

Edmunds says

The Prius Prime's disappointing electric range test results shrink the gap between these two plug-in hybrid contenders even as the Toyota's more powerful acceleration gives it an advantage over Kia's Niro PHEV.