Tesla has made inroads into the compact luxury SUV market with the all-electric and all-new Model Y. Buyers longing for the crossover version of a Model 3 have gotten their wish since deliveries began in March.

But not every new owner is taking it out on the track to try to match Elon Musk‘s claim of a 0-to-60 mph heat of 3.5 seconds. Instead, some owners are taking their new EVs apart. What inspired this sudden curiosity to tinker with a brand-new car? Here’s a hint: it has to do with the Model Y’s range.

A short overview of the Model Y

The Tesla Model Y shares the platform, equipment, and many features of the Model 3. It sits more upright than the Model 3 and has a hatchback style like the Model X but without the falcon wing rear doors.

The exterior styling is highly sculpted and simple just like the other Tesla models. The SUV’s interior is minimalistic and spare, with narrow A- and B-pillars and lots of glass, including a panoramic sunroof. It’s hard to overlook the huge 15-inch touchscreen, which is how the driver controls key functions in the vehicle.

But what makes the Model Y different than Tesla’s previous models is its improved range. According to Consumer Reports, Tesla has addressed buyers’ range anxiety by equipping this model with good batteries and making it more energy-efficient. The upstart car manufacturer has increased its estimate for the SUV’s range from 280 to 315 miles on a full charge for the Long Range variant.

By increasing the Model Y’s range so impressively, Tesla has issued a challenge to rivals such as the Audi e-tron, the Jaguar I-Pace, and upcoming models from Porsche, Volvo, and others. Right now, no automaker can match the Model Y’s energy efficiency of 4.1 miles per kilowatt-hour. Tesla has also reduced the SUV’s weight, increased its aerodynamics, and improved its equipment.

Many of Tesla’s methods of increasing the Model Y’s range and energy efficiency are fairly straightforward. But there’s one that the EV manufacturer has not mentioned publicly, and it’s one that an inquisitive owner discovered on his own.

The Model Y’s hidden range secret

The owner, YouTuberDÆrik, stumbled upon the key to the Tesla Model Y‘s better range by simply removing the trim over its “frunk” (front trunk) and looking around. Among components such as a windshield fluid reservoir, a large air intake, and an active grille shutter, he found a heat pump.

Why would Tesla install a heat pump in its Model Y, and why should we care? The reason, as Nick Yekikian of MotorTrend pointed out, is energy efficiency, especially in cold weather. Previously, Tesla has depended on electrical resistance to warm its models’ cabins and batteries. Electrical resistance is the opposition to current flow in an electrical circuit. This opposition transforms electrical energy to heat.

Usually, this form of electrical resistance is an efficient way to generate heat since the amount of energy going in is equal to the amount put out in the form of heat. But in extremely cold weather, the heat used to warm the car’s cabin takes energy away from the same energy reserve used to supply the battery to move the car. This shift of heat energy from the battery to the cabin results in a reduced driving range.

By comparison, the Model Y’s heat pump doesn’t impact the SUV’s driving range directly. It runs the air conditioning refrigerant in a reverse circuit to cool the outside and send warmth back into the cabin. When the A/C is turned on, the compressor squeezes the refrigerant into a liquid and pushes it into the cabin, The liquid vaporizes, which pulls heat out of the interior to cool it. 

The heat pump reverses this process and evaporates the refrigerant in the exterior heat exchanger. The interior heat exchanger works as a condenser to compress the refrigerant, which then releases the heat to the cabin.

Tesla hasn’t released any information of substance about how exactly the Model Y’s heat pump works. It’s hard to say if other upcoming Tesla models will use this system in the future. However, other modern EVs like the Mini Cooper SE, the Nissan LEAF and the Kia Niro all use heat pump systems to warm the cars’ cabins in cold weather.

How well does it perform?

Four powertrains are available on the Tesla Model Y: the Standard Range, Long Range, Long Range with Dual-Motor All-Wheel Drive, and Performance. The first versions of the Model Y that have been rolled out are the Long Range and Performance trims, according to Consumer Reports. These configurations start at $48,000 and $61,000, respectively. The Standard Range model won’t start production until early 2021, and it’ll be priced at $40,200.

The Long Range model with all-wheel drive does respectably well on the track, hitting a top speed of 135 mph and a 0-to-60 mph heat in 4.8 seconds. The Performance trim, according to Elon Musk’s claim at the Model Y’s introduction, has a top speed of 145 mph and can do 0 to 60 mph in 3.5 seconds.

At this point, nobody knows how many miles the Model Y’s secret range-saver actually recovers in winter weather. But what’s clear is that all Model Y variants have excellent driving ranges. Buyers who choose the Standard Range should expect to get about 230 miles on a full charge. The Long Range model with AWD is estimated to yield about 315 miles of range, and the Performance will also get 315 miles on a full charge.

So, who knows what else might owners find in their new Model Ys. Given that Tesla is well-known for surprising owners with wacky Easter eggs in their vehicles, anything is possible. But the secret range-saving heat pump is an excellent start.