But midway through the disc, in the midst of a psychedelic freak-out during "Turn This Car Around," the artist urges us to "turn this car around -- I'm going back!"

"Highway Companion," the third solo album of Petty's career and his first since "Wildflowers" (1994) without the band that has backed him for the last 30 years, turns out to be less about forward momentum and forging ahead in life than it is about looking back. Though he's only 55, Petty is talking like an old man at the end of a long and very hard road, a theme he sums up in a line from another song from the new disc: "You're flirting with time, baby / And maybe / Time, baby, is catching up with you" ("Flirting With Time").

Early in the new millennium, Petty endured one of the most difficult periods of his life. In the late '90s, he separated from his longtime wife and lived in seclusion for a time in a shack on the Pacific Palisades, battling clinical depression. He rebounded in 2001, when he married his current wife, Dana York. But in 2003, a year after he fired the Heartbreakers' longtime bassist, Howie Epstein died of a heroin overdose, and that loss prompted the songwriter to start thinking about his own mortality.

By all accounts, life is pretty good for Petty these days. But he's is nonetheless hinting that this summer's tour by the Heartbreakers may be his last, and he's starting to consider what kind of legacy he'll leave behind in the music world. "I've been such a nut, I wonder how long I'm gonna live sometimes. I've just lived so hard," he told Jaan Uhelszki in an interview for Harp magazine, one of only a handful he's done to support the new album. "I think a lot about what time I have left and what kind of mark I want to leave. I might quit the road. I think I've had enough of that -- but I haven't had enough of playing."

Indeed, with the exception of a few contributions from longtime Heartbreakers guitarist Mike Campbell and producer Jeff Lynne -- who filled the same role on Petty's solo debut, "Full Moon Fever" (1989), as well as performing with him in the Traveling Wilburys -- Petty handled all of the instruments in the studio for "Highway Companion," including rhythm guitar, drums, harmonica, electric piano, bass and lead, and backing vocals. Yet while he clearly had some fun hammering out a few of his trademark jangly rockers, including "Flirting With Time," even the handful of upbeat tunes have somber themes or cautionary warnings about living too hard or too fast.

The deceptively bouncy "Ankle Deep" is about a thoroughbred that breaks its leg in a big race; presciently, it was written a year before Kentucky Derby winner Barbaro's career-ending injury. "Down South" shows flashes of Petty's sardonic wit when he sings about wanting to "Create myself down South / Impress all the women / Pretend I'm Samuel Clemens / Wear seersucker and white linens," but the ostensible purpose of his trip to the Dixie where he was raised is to "sell the family headstones [and] make good all my back loans," as if he's making preparations for his own funeral. Even the somewhat forced declaration about needing to party hearty over the "Big Weekend" -- "I need a big weekend / Kickin' up the dust" -- is tempered by the observation that "if you don't run, you rust."

That last line is an obvious nod to Neil Young's "My My, Hey Hey (Out Of the Blue)," with its notion that "It's better to burn out / Than it is to rust," an idea that has all too often been misinterpreted by younger artists hell-bent on self-destruction, a la Kurt Cobain in his infamous suicide note. But the Young song that much of "Highway Companion" actually recalls is "Old Man," with its poignant vision of both the sadness and the nobility of aging. Like Young, Petty isn't bemoaning the fact that he has entered the twilight of his life; he's looking back and thinking that it's pretty darn cool to have reached this point and had so many incredible experiences along the way.

With varying degrees of quiet, largely acoustic arrangements, melancholy productions, haunting blues underpinnings and laid-back tempos, the majority of the songs on "Highway Companion" fit this bill -- "Night Driver," "Jack" "Square One," "Damaged by Love" and "This Old Town" among them. Regardless of what you may have heard, by no means does this make for a great driving album; you'd be better off taking a handful of Ambien before getting behind the wheel than listening to this on a long road trip and expecting it to keep you energized. But "Highway Companion" is another gorgeous, heartfelt, wistful and moving statement from a great artist who really has no reason to think twice about his place in rock history.

Petty can sound tired of the grind and claim to be questioning why he'd want to continue the rock 'n' roll circus he's been part of for three decades now. "It's hard to say who you are these days, but you run on anyway, don't you?" he sings in the opening track, "Saving Grace." But we are all the richer for the postcards he sends along the way.

Tom Petty and the Heartbreakers perform at the Charter One Pavilion on Northerly Island with the Strokes opening at 7:30 p.m. on Sept. 14 and 15. Tickets are $49.50 to $89.50 through Ticketmaster, (312) 559-1212.