Popular outside the United States, the sport involves driving great distances on public roads, as opposed to a closed track. The racing, however, happens on timed, competitive sections called "special stages," which are closed to public traffic and range from a few miles to more than 20. The winner of the race has the fastest combined time from these stages.

In October, Riches placed second overall in the six-day Dunlop Targa rally race in New Zealand, driving his new, modified Porsche 997 GT3 RS. He had hoped only for a top-five finish out of some 170 competitors, he says, but he did even better, placing first in class and winning the Master’s Award, which goes to the highest-place finisher over age 50. "It’s good for us old guys to feel competitive," he says.

This "old guy" doesn’t plan to slow down any time soon. He says his wife, a physician in Naples, encourages his racing, just as she always has—even when a crash in 2000 left him wheelchair-bound for months after he crashed into a wall at 140 miles an hour, breaking many bones.

Did his wife want to wheel him off a cliff for getting himself into that situation? Riches laughs.

"That wasn’t a problem," he says. "I got a motorized chair."