As the choking smoke became thicker, the shocking realisation dawned: the car, not the desert, was on fire. An emergency braking manoeuvre, followed by a scrambled rush for the source revealed a quickly-melting battery case, covered in flames.

Surely this couldn't be happening, 100 kilometres from the nearest garage? Volkswagen Beetles, known the world over for reliability and dependability are not supposed to be prone to spontaneous combustion.

But this was a very real blaze, which had to be dealt with using the only piece of luxury equipment on board, pragmatically installed by the hire firm in place of a cassette player, air conditioner or radial tyres.

A fire extinguisher, blasted at full-tilt, doused the flames, left the rear seats covered in foam, and reduced the driver's palpitating heart-beat considerably. Amazingly, the car still managed to stutter into action.

Not every driver is so lucky when crossing the Central Desert in the Baja California region of Mexico; burned-out, clapped-out and abandoned car and truck shells litter the fringes of the road.

Driving in Mexico is an option few overseas tourists take up, for obvious reasons. The stories about horrific roads, slapdash driving and shack-like hotels are all absolutely true.

The majority of cars which head south of the US border, through the scruffy border town of Tijuana, are wealthy Americans, zooming across the desert as quickly as they can, whizzing down for Sea of Cortez fishing trips.

The Americans' gleaming, dent-free cars are generally inhabited by just two imperious people, contrasted with the beat-up, family-packed trucks driven by Mexicans.

Somewhere in-between, plodding and puttering along, are VW Beetles, hired by visitors in no need of speed for their peninsula expeditions. It takes a certain verve and nerve to contemplate getting behind a car wheel in Mexico, let alone in a primitive VW Beetle.

The automobile is a relic from before World War II, designed and built on the orders of Adolf Hitler as a car which ordinary people would be able to afford.

Its production run lasted longer than any model ever, until it was finally superseded by sleeker, faster models from the automotive drawing boards of Germany and Japan.

Nobody told the Mexicans and Brazilians, though, who refused to bow to the whims of vehicular fashion and kept on making the ugly, air-cooled Bugs.

The Beetle Bugs are well suited for erratic and potholed Mexican roads: the sturdy frames reel with the frequent blows from below like journeyman boxers.

There is nothing much that can go wrong, unless the car is saddled with dud replacement components - such as a battery that chooses to perform pyrotechnics.

Getting the part replaced in Mexico was like being an extra in one of those tasteless American sitcoms which mercilessly poke fun at Mexicans.

This particular Mexican mechanical troupe fitted the stereotype, spending a full five minutes head-scratching, another five in heated debate and a full 20 performing the simple manoeuvre of hefting the battery out and putting in a new one.

The entire procedure, though, was done with humour and warmth rarely found on an American filling station forecourt, and there was no expectation of a huge tip or phoney exhortations to have a nice day.

Catching fire was by no means the most dramatic part of the Central Desert experience. That came at night, while bumping along a trail, en route to a ranch guest room, the only accommodation generally available in the desert's inner sanctum.

In the heart of the desert there are few people, no industry and only a smattering of cars, which means absolutely no pollution.

That, in turn, ensures a vision of the stars which is simply mind-boggling. The tranquillity of the surroundings and the sheer scale and magnitude of the planetary expanse made it a humbling, scary experience.

During the daytime, the desert could be threatening for different reasons.

Guide books warn against straying off the main paved metal road, which winds through the cacti and scrub, and into all kinds of unseen and unknown dangers.

Rattlesnakes do not take kindly to clumsy invaders trampling around in their territory; cruel-featured vultures perch expectantly, ready for any easy pickings put on their plate.

Coyotes, when they appear around dusk, send shivers down the spine with their padded prowl and piercing yelps.

And there is nobody around to help in an emergency. On the 600-kilometre strip of desert road there are maybe a couple of cars passing each hour; on the tracks it is more like a donkey every few days, or a four-wheel drive a week.

Filling stations are few and far between, and when they do shimmer into view, they are shacks with one barrel of gasoline, operated by children with a solo piece of rubber tubing and a suck-to-start method of pumping fuel.

Apart from filling stations, the odd hamlet and a few ranches, the only other settlements are long-abandoned Catholic missions, built to the specifications of uninvited Spanish priests.

The religious men established a chain of churches, all the way along the Baja California strip, converting the local Indians and passing on Western diseases, which eventually wiped out the natives.

The desert was seen by the holy men as an evil which had to be endured to get to the more bountiful ocean region which lay south and east.

That pretty much sums up the attitude of wealthy Americans today, who motor down in their monster mobile homes towards the fine fishing grounds of Baja's southerly coastlines.

The vans and trucks proceed at a blistering pace, disinterested in the scenery and unwilling to try the delicious peasant food en route.

Driving by Bug, admittedly with the same idyllic final destination in mind, there was little option but to enjoy the surroundings.

With a top speed of 90 kilometres per hour, there was no hope of making the journey south to the Sea of Cortez in less than two days. In a Bug, the scorching-heat scenery goes by at just one speed . . . slow motion.