Despite being surrounded from an early age by the usual trappings of advanced rock'n'roll hedonism, particularly after his album Harvest became the best seller of 1972, Neil Young has never been your average rock star, and this not your average rock star autobiography. There is a little bit of weed and cocaine  quite a lot, actually, but not flaunted, as it were, under the reader's nose  and some discussion of guitars and the occasional backstage tantrum, but rather more about his son Ben, who was born with cerebral palsy and is quadriplegic, and his own childhood polio and the brain aneurism that attacked him in 2005.

Young is a natural obsessive and a bit cantankerous, which makes an interesting combination. Unlike Bob Dylan, whose Chronicles: Volume One seemed intent on telling the real story, albeit with embellishments and occlusions, he seems uncertain of the core purpose of the project. Young stopped drinking and smoking shortly before starting to write, and it may be that the book represents a sort of displacement therapy. But those drawn over the last half-century to his high, strained voice and doggedly affecting ballads will find plenty here to flesh out their portrait of a man who prefers amplifiers with valves and cars with carburettors, and resents the way today's music is marketed "like a cool pastime or a toy, not a message to the soul".

Having grown up watching his father, a prominent journalist and broadcaster in Canada, tapping out columns for Toronto's Globe and Mail on a typewriter, he has declined to avail himself of a ghostwriter's services. His distinctly unplugged prose can plod along in an artless, ruminative sort of way, or it can  very occasionally  take wing. The style turns out to be as unpredictable a combination of awkwardness and grace as his music, lurching from sudden insights  "the muse has no conscience", he notes, meditating on his readiness to do the dirty work of firing colleagues who fail to meet his standards  to the occasional aside of such startling banality that the reader pauses, searching in vain for a redeeming irony: "California really is beautiful if you've never been there. It's worth a visit for sure." There are lots of exclamation marks, and even an "OMG", which sounds odd coming from the pen of a 66-year-old man.

He begins by describing the act of unwrapping a present from his wife, a rare piece of vintage switchgear for the elaborate model train set he keeps at his principal home, the Broken Arrow Ranch, in northern California (there are other homes in Hawaii and Malibu). He built the train set many years ago with Ben, who is now in his mid-30s. Many of the associated items  locomotives, carriages, accessories  are kept in display cases, whose windows Young carefully polishes.

A couple of pages later he is telling us about a pivotal moment in his life: his purchase of a 1953 Buick Skylark, a car he had desired since his childhood, after seeing one belonging to a friend of his father. "It was brand-new and made a large impression on me," he writes, "with its beautifully designed grille, tail-lights and an overall shape that featured a kind of bump or ripple in the lines at about the midpoint, accentuated by a chrome strip that mirrored it." The coveted Skylark became the centrepiece of a collection that eventually expanded to about 35 cars of character, many of which we meet at some point in his tale, as when he is taking his wife on a first date (baby-blue '49 Cadillac convertible), vainly searching for the location of the TV show 77 Sunset Strip on a first trip to Los Angeles from his Canadian home ('53 Pontiac hearse), or cruising the Hollywood Hills between recording sessions for his first solo album ('34 Mulliner-bodied Bentley coupe).

Soon he moves on to the two matters that seem to have become an even more pressing obsession, and on behalf of which the book occasionally turns into a propaganda vehicle. The first is an audio reproduction system called PureTone, with which he hopes to rescue the recording industry from the digitally compressed sound of the iPod. "Today, music is presented as an entertainment medium, like a game, without the full audio quality," he writes. The second is the Lincvolt, an old Lincoln Continental adapted to run on electricity and ethanol with the intention of demonstrating to auto industry sceptics that if such a beast can be turned into an ecologically neutral device, then anything is possible. The Lincvolt's job is to rescue the planet.

"I put in the money to do it myself," he says of his projects, "and do whatever I need to do to get the money, promise that I will deliver a record and get advances, anything I can do to get the cash to make something happen the way I envision it. So I get into a lot of trouble, although I also get a lot of things done."

His relationship with the digital age provokes his most interesting meditation on his first-hand experience of changes in a musician's relationship with his work and his audience. "Any experiment I try onstage is thrown up on YouTube, where people who think they know what I should be doing start shooting holes in it before it's even finished," he writes. "This is the single most daunting challenge the internet has provided, along with all the good things. The stage used to be my lab, where I could experiment in front of a live audience and see how it reacted and  more important  how I felt while I was doing it  Now I try to work things out in private while I develop ideas. That way I have a chance to present the first time to a large audience. Unfortunately, that is not as adventuresome for me."

None of this has much to do with David Crosby, Stephen Stills and Graham Nash, the three musicians with whom, in the early 1970s, he toured and recorded as part of what was probably the most popular (and high-earning) band of its time. They are dealt with in a handful of pages that end with a crisp explanation of a break-up largely rooted in his discontent: "But then came the fame, the drugs, the money, houses, cars and admirers; then the solo albums  In the end, it became a celebration of ourselves, and there was no way to keep that going."

For all Young's engagement with serious issues, Waging Heavy Peace is not without its reminders that he achieved his celebrity during an easily satirised time of excessive reward and immoderate self-indulgence. When an aide calls to break the news that his beloved customised tour bus, known as Pocahontas, has caught fire and burnt out, he has its remains conveyed to his ranch and buried in a eucalyptus grove.