According to the Environmental Protection Agency, Tesla drivers should be able to travel 265 miles per charge in the top-level Model S. According to Tesla, they should hit 300 miles. But last weekend, a Florida college professor recorded the highest-ever range in an electric car: a whopping 423.5 miles without even draining the battery.

David Metcalf, a researcher at the University of Central Florida, decided to take his new Model S on a calculated adventure along the Panhandle. With his 12-year-old son Adam, Metcalf managed 17 nonstop hours before the dashboard flashed "Charge Now." It was a seemingly impossible feat that began as a cocky tweet from Tesla CEO Elon Musk in May, who promised prizes to the first 10 Model S drivers to exceed 400 miles per charge.

So far, Metcalf is the first and only.

"My professional training is in Information Systems, so my son and I approached the challenge the same way I would validation testing on any technical research project," Metcalf, 43, told MSN Autos. "This kept me mentally alert, as did having a good copilot, my son Adam."

Do the math and you realize there's a big caveat to this story: Metcalf averaged 25 mph. For 17 straight hours.

"We planned the route very carefully to avoid all interstates and stay on slow roads most of the time," he said. "People did pass us and some stretches were four lanes, but we had 7.5 hours where we only saw 20 cars. This was through the central and south parts of wild Florida including the Everglades and other wildlife parks."

David Metcalf poses with his record-setting Model S. (UCF)

Unlike most hypermilers, Metcalf and his son didn't suffocate themselves to break the record, as Florida winters, especially at night, are actually tolerable without air conditioning.

The excruciatingly slow speeds and agonizing hours circling southern Florida didn't bother Metcalf one bit. Basically, the man doesn't have to sleep. In 2011, he ran a 100-mile ultra marathon that took him more than 26 hours to finish. In between training, he surfs.

Metcalf's Model S wasn't exhausted, either. To be safe, he called for a tow from AAA, but the car was still running with the A/C and radio for 45 minutes while they waited. Metcalf says he didn't want to risk ruining the battery by completely draining it.

Currently, Guinness World Records is validating his trip. The previous record was set in Australia three years ago with a Tesla Roadster, which topped 313 miles on a single charge.

While Musk has been silent on the prize (it will be revealed next week), Metcalf doesn't care. He's donating whatever money might be at hand to the university and its Haiti relief efforts.