Our first journeys mark us. Whether a memorable family holiday to the Dordogne, a raucous school trip to Madrid or a first independent trek across south-east Asia, early experiences stay with us, often dictating travel preferences and passions for the rest of our life. The phenomena can't be put down simply to a hankering for familiarity. Few of us want to make sentimental journeys for the rest of our life. Rather we go back because our first, impressionable visit changed us, and so a return enables us to better understand ourselves through the changes in the destination. I am who I am in part because of this place.
At the age of 18, as a full-blooded punk (with a secret passion for Barry White), Hugh Thomson flew to Mexico. Intoxicated by anticipation, he falls for a story spun by a fellow passenger. Want to make money in Mexico? Buy a car over the border in Texas, drive it across the country and sell it in Belize for a handsome profit.
As soon as he can arrange it, Thomson is in El Paso – the biggest "used-car lot of America" – negotiating for a second-hand, electric blue Oldsmobile 98, one of the largest gas-guzzlers ever made by Detroit. He parts with $500, cranks up the stereo and hits the road. Unwisely, he has no insurance or licence plates. Also he doesn't know how to drive, an oversight which results in him slamming into a half-a-dozen vehicles at his first multi-storey parking garage. But the straight, empty highways of northern Mexico prove to be a good place for him to learn, even if he needs to pull on to the hard shoulder whenever he spots an approaching Greyhound bus.
Over a couple of thousand miles and months, he heads south, pausing to surf on the Pacific, hang-out at the Rancho Grande and be rescued by a friendly hippie in a Winnebago. In a museum to Pancho Villa, he meets the revolutionary's widow ("this was a bit like finding Lenin's widow tending his mausoleum in Moscow"). In Mexico City, he indulges in magic mushrooms, pursues an unattainable older woman and, after an unsettling encounter with the police, gets a driver's licence (no need for a test - a couple of bribes did the trick). He pays for the trip by working as a translator. He even manages a bankrupt golf hotel for a week, living off steak and champagne, drinking the wine cellar down to its last dusty bottle, all the while suffering from amoebic dysentery. But always he is looking ahead to the big pay off in Belize.
Mile by mile he falls in love with Mexico, its people, customs and intoxicants. In the small town of Cholula he finally loses his heart, sealing his destiny to return to the Americas. "The bells were pealing, there was the excited laughter of unseen children coming from somewhere near by and the smell of roasting chocolate and peanuts from one of the little roadside stalls," he writes. "A band were playing at the next church down the way … and the sound carried in the evening air with the clarity of a cinema soundtrack. I had what I can only describe as an epiphany, a moment of lucid and complete surrender, in which the whole of Mexico seemed to come up inside me and I felt that this was a moment that would never end and that wherever I went I would not leave this place.'
Navigation without a map is difficult in Latin America, Thomson points out, because it's considered rude not to give directions. So locals confidently advise drivers to go "straight ahead, follow your nose" without having the slightest inkling of the right route. Nevertheless, Thomson manages to cross the border into Belize (on forged papers), but once there he finds that the now-battered Olds 98 is all but worthless – for the most hilarious and unexpected reason. Penniless, he explains his predicament to a hotel manager.
"It's obvious," (the manager) said, as if to an idiot. "Take the car down to the beach. Pour gas over it. Torch it. And claim the insurance."
"There is no insurance."
"In that case you're fucked. Have another margarita."
Thirty years later, Thomson returns to Belize to complete his "unfinished journey". The framing works as a literary device but - perhaps because he had just lost his marriage, his house and much of his money – the last chapter lacks the energy and cohesion of the original trip. Yet Tequila Oil remains an atmospheric and youthful romp. In a way it is the first instalment of his now-complete trilogy, his Cochineal Red and The White Rock being two of the finest books on Latin America of recent years. 2009 may only have begun, but I doubt I'll read a more delightful, celebratory and honest travel book this year.
• Rory MacLean's latest book Magic Bus: On the Hippie Trail from Istanbul to India is published by Penguin. His UK top tens Stalin's Nose and Under the Dragon are republished by IB Tauris.
