Tell Jay Leno that his life story — his rise from a Rolls Royce mechanic in Boston to one of the most popular comics in the country — sounds suspiciously like the great American success story, and he’ll say indifferently, “That’s fine … it’s opposed to the flip side: a drug induced stupor.”

Tell him that people are making fun of his protruding profile — the one caricaturists live for — and he’ll say confidently, “I don’t mind. I make my living making fun of other people, so if they make fun of me, that’s fine.”

Ask him if he wants to inherit the job as “The Tonight Show” host — a question late-night groupies are dying to have answered — and he’ll say quickly, “That’d be nice. If and when that time ever comes, would I do it? Sure.”

Talking to Leno from “The Tonight Show” dressing room is surprisingly easy and relaxed. He talks about his outrageous schedule that brings him to Maine on Saturday, Los Angeles on Sunday, Alaska on Monday, and Hollywood again on Tuesday for his regular slot on “The Tonight Show.” With more than 300 gigs a year, it’s a wonder Leno doesn’t stay in a perpetual state of indigestion.

“It gets a little crazy,” he says. “But you get used to it. I used to work for a living. I would hate to have a real job.”

He talks about his collection of vintage motor cycles and classic cars, how tinkering with his extensive collection is how he relaxes. Later that night, when he interviews Patrick Swayze on “The Tonight Show,” he says his garage full of vehicles is a tax write-off.

“Well, Johnny calls and I gotta get here quickly sometimes. … that’s what I tell the IRS.”

Leno has been knighted with the title of “permanent guest host,” and is the only person subbing for Johnny these days. It’s a far cry from his childhood days in Andover, Mass., or his summer camp days in Ogunquit and Kennebunkport, but right on target with his dreams of being a successful comedian.

Like most who are in the business of drollery, he imagined himself sitting in Johnny’s chair, but never thought it would happen. Consequently, his loyalty to the master of late-night comedy is unflinching.

“I try to do the show in the same style that Johnny does it,” says Leno. “You know, you try to have monologues that hopefully are funny and don’t do anything that embarrasses the show, and don’t take any cheap shots and try to keep the standards as high as Johnny does.”

The absence of “cheap shots” seems to be the only gimmick of Leno’s act. He has even been called a “clean comic” because his repartee never crosses the boundary between wry and offensive.

“Comedy is supposed to be the underdog making fun of the big guy,” says Leno.

“I get annoyed when I see humor that is fascist or racist or misogynist or anti-semitic. I defend people’s right to say whatever they want. I just don’t particularly care for it. I wouldn’t mind if there was a joke there. It’s always funny to me how if you make fun of ethnic groups or make fun of women or something like that, then you’re on the cutting edge, but if you go after our foreign policy or the savings-and-loan scandal or Washington, that’s just like getting a Walt Disney G rating.”

For Leno, the best punchlines come right from the day’s news headlines. He listens to the three major TV networks and reads the newspaper for most of his material, and then develops a monologue that is “bipartisan” in its ruthlessness to politicians.

“My job is to kind of degrade and humiliate the whole system fairly equally,” says Leno, who collaborates with “The Tonight Show” writers for his monologues.

When Leno goes on the road, however, he writes his own material. His night club and concert acts include narrative and some regional humor. But the topics that seem to get the laughs, he says, are the ones that have always gotten laughs: sex, money, drugs and alcohol.

“Those things will always get laughs because that’s something everybody knows. Everybody’s had brushes with sex, money, alcohol and drugs.”

Leno, however, keeps his own act clean. His lifestyle, fast as it is, is remarkably free of vices. He doesn’t smoke, drink or do drugs. The worst he could be accused of is something he readily admits: “Cool Ranch Doritos are my favorite. I try to eat my body weight everyday.”

Jay Leno will perform at 8 and 10:30 p.m. on July 21 at the Maine Center for the Arts. Tickets are still available for the 10:30 p.m. show and may be purchased by calling 581-1755. Leno also will perform at 7:30 p.m. July 20 at the Portland City Hall Auditorium. To buy tickets for the Portland show, call 1-800-382-8080.