The loneliest Mercedes

There is only one 1935 Mercedes 150H Sport Roadster: Martin Gurdon takes it out on the streets of Los Angeles.

Valuing the 150H is tough because there isn't another one to compare it with.

In car-loving Los Angeles, red, mid-engined sports cars barely raise an eyebrow. But the one I'm driving is causing a stir. Burly men in huge pickup trucks goggle through smoked glass windows and make thumbs up signs. At every stop, people cluster round the tiny car. "That's cute," says one bystander. Another reckons she's never seen anything like it. And she would be right, because the car, a 1935 Mercedes 150H Sport Roadster, is unique. It's not known how many were built, but it's between two and 20, and this is the only survivor.

After Mercedes bought the car back from a private owner in the 1950s with just 44km on the clock, it sat in a German museum. Suggestions about bringing it back to life were greeted with stern head shaking by Mercedes management. The car was precious, and taking it to pieces to restore it could damage parts that would be impossible to replace. Apparently, the powers that be were worried that they'd end up with an expensive pile of bits.

Their change of heart represents a startling turnaround. Not only is the car now very much alive, but it's also being driven on public roads, mixing it with towering yellow school buses and gawking commuters. And, as a huge act of faith, Mercedes invited journalists to get behind the 150's slim, spoked steering wheel and take it for a spin on Los Angeles' sun drenched streets. Valuing the 150H is tough because there isn't another one to compare it with. But a Mercedes chaperone described it as, quite literally, a million-dollar car. Anyone wrapping it round a mailbox wouldn't be popular.

Bringing it back to life in the US rather than Germany isn't as strange as it seems; the company's Irvine-based Classic Center, a mix of museum and vehicle restoration workshop, is a repository of old-car expertise. Mercedes does have another Classic Center in Fellbach, Germany, but it opened the Irvine shop in 2006 because the US is the world's largest classic car market. One of its experts there is the cheerful, impossibly young-looking Nate Lander, whose team stripped the 150H of its body, threw away its brittle and potentially flammable wiring, gave it a mechanical overhaul that was little more than a glorified inspection - the car still has its original head gasket - and had it running less than two months after rolling it out of a shipping crate.

Some people might treat the car with kid gloves, but Lander is entirely matter-of-fact. He doesn't seem worried about it overheating under the relentless Californian sun, suggesting that there will only be a problem if it starts to steam. Apparently Mercedes fitted kettle-like whistles to some of its rear-engined models so they would shriek if things got too hot. Although almost horizontally relaxed about the 150H's 1,500cc, overhead cam, water-cooled engined, which sits ahead of the back wheels, Lander asks the assembled hacks to be nice to the gearbox, reminding them with a smile that its components are 75 years old.

The 150H was the pinnacle of a range of highly innovative, rear-engined small cars Mercedes built from 1934 until the outbreak of the Second World War. These were a response to the economic crash of 1929, which killed many up-market car makers of the day and caused the ones that survived to look at making smaller, cheaper models with the same qualities that made their bigger siblings desirable. This has a strong contemporary ring, doesn't it?

German and Czech vehicle designers had been experimenting with rear-engined cars since the 1920s, reasoning that dangling power units behind the rear wheels freed up passenger and luggage space ahead of them. Mercedes embraced this with its 130H. In an era when rods and cables were often used to make small cars stop, the 130H had hydraulic brakes, along with a cleverly simple, tube-like sub-structure on which to hang the engine and fully independent suspension and attach the pressed steel body (wood and fabric was then still being used in some car's bodywork).

With Germany's Autobahn high speed road network growing at the time, the baby Mercedes was engineered for motorways. It boasted a three-speed gearbox with an overdrive that could be engaged at speeds above 65kph without touching the clutch pedal, to make overtaking or high-speed cruising easier. But Mercedes soon discovered that hanging the engine behind the back wheels can create tail-wags-dog handling. So it went to the great expense of designing a completely new transmission for its next aft-engined baby, the 170 saloon, so the engine could be shifted forward slightly to help the model's balance. This rounded car bears a strong resemblance to the VW Beetle, which isn't surprising because Mercedes actually built Beetle prototypes in the 1930s for Volkswagen.

The 150H was intended both for competition and as something to sell to the well-heeled. Being a two-seater, space wasn't at a premium, but driving dynamics were, hence shifting the engine into the middle, between the axles, to create a car with balanced handling. Even now, this is seen as a bit exotic, but three quarters of a century ago it was cutting edge. The 150H and its saloon siblings - examples of which were on hand in LA - have a no-expense-spared feel to their designs. They were engineers' rather than accountants' cars; many drivers found them just too weird and too expensive, so sales never really took off. And given that German cars of their era have a still-awkward association with Nazi rule, it's only quite recently that Mercedes has felt comfortable celebrating the design creativity that went into them.

The company points out that the current smart car is rear-engined, but it does so without commenting on the fact that the design was started outside the company, or that making money from it has been difficult - something it has in common with the pre-War models. As a driving experience, the 150H and its siblings mix the familiar with the weird and frankly remarkable, showing both how far cars have come in the past eight decades and how good some were back then.

Once the slow starter motor has churned the engine into harsh-sounding but oddly smooth life, the solid transmission, with first and overdrive up and out on dog legs in the shift pattern, takes a bit of getting used to, especially the pantomime of lever shifting while ignoring the clutch pedal for overdrive. But the dainty, open body feels rock-solid - it would shame some modern convertibles - the ride is surprisingly comfortable and both the steering and brakes belay the 150H's age.

Bowling along between traffic lights and stop signs, we don't attempt to explore its 124kph top speed - which sounds slow now, but it wasn't in the mid-1930s. It's hard not to be impressed by how well this remarkable old car works. With its whirring cooling fan, whining gears and other-worldly looks, the 150H is an incongruous site in the anonymous, low-rise LA suburbs; a case of Fritz Lang meets the Stepford Wives. Yet like Lang's early films, it still manages to look both very old and very futuristic. [e-mail]