When he was 6, the sight of a Land Rover cruising down his street caused Uli Sommer to fall in love with cars. Two years later he made a discovery that thrust him into a state of permanent guilt-ridden ambivalence about his obsession — namely that cars run on petrol and that petrol is in finite supply. In his teens Uli got his driving licence just as his environmentally conscious parents decided to sell the family hatchback.

But Uli’s obsession persisted, and it combined with a talent for making things: a three-legged bunk-bed and a parent-toddler tandem are among his private inventions. As an adult Uli had a successful career as an engineer, during which, still passionate and still torn, he designed parts for a firm that supplied BMW and Mercedes. Today, however, he navigates his home town of Munich only by bicycle.

The question is, can a bicycle-riding environmentally conscious car fanatic spark an automobile revolution? Uli thinks so — as do many of those who have come to the 76th Annual Auto Show in Geneva to clap eyes on Uli’s revolutionary idea — the Loremo, a car that runs for 110km on an anorexic 1.5l of fuel — meaning that it manages 186 miles to the gallon.

Say you drive 20,000km a year in the average small car. By the end of the year, your car will have consumed 1,600l of fuel, for which you would have paid between £1,440 and £1,506, depending on whether you used unleaded, super unleaded or diesel. If you’d been driving the diesel-powered Loremo, however, you will have paid only £282 for your 300l.

You probably haven’t heard of the Loremo. Until this week, Uli’s fledgling idea was merely an internet rumour and a concept being painstakingly realised by a group of 13 car fanatics from Germany. The car, which will cost between €11,000 and €18,000 (£7,512 to £15,000) and can achieve speeds of up to 250kp/h (155mph), won’t be available until 2009.

And you won’t find it at your local car dealership. Instead the Loremo will be for sale on the internet and at petrol stations and department stores across Germany, Italy, France, Spain and the UK.

The Loremo began life in earnest six years ago when Uli set up a company with Stefan Ruetz, his former boss, and Gerhard Heilmaier.

Although Ruetz still runs his own engineering company, Heilmaier — like Uli himself — chucked in his job to work full time on the idea. Heilmaier has personally invested €1 million of the money he made when he sold his business supplying parts for the German car industry. “You either believe in an idea or you don’t,” he says. “You can’t be half pregnant and you can’t only half believe .”

What does an automotive revolution look like? In this case it is low-slung like a Porsche but narrow like a Fiat Cinquecento. The interior is spartan with a single LED screen combining the roles of telephone, MP3 player, electronic navigator and speed gauge. There are four bucket seats, and the steering wheel is attached to the roof, itself a door. “This makes Loremo as easy as stepping into a bathtub,” claims the brochure. A pod on wheels, the Loremo deliberately thumbs its nose at modern car design.

Common sense tells us that soaring fuel prices should have produced a supply of lightweight cars. Instead, the opposite has happened. Cars have generally become bigger and heavier. Even the once wafer-like Mini has put on 695kg (1,532lb) since its redesign and now weighs in at around 1145kg. A Loremo weighs 450kg.

It has always exasperated Uli that while aircraft and bicycles are designed to be energy efficient, the drivers of cars wanted, or thought they wanted, or were told they wanted (since nobody had bothered to produce an alternative) more cupholders, more padding, more horsepower and the perceived, yet actually negligible, safety advantages of more bulk. And, since the oil crisis of 2000, they’ve really been paying for it.

Uli threw all that received wisdom out of the window. “I wanted to make a car that was beautiful and elegant, that was fun to drive, but that could also save you money and be sustainable.

“I imagined a car that tapped into the joy, the very essence of what driving means. With a lot of modern car design we have lost that.” To do this the Loremo team persuaded a young and pioneering designer, Tobias Hoffritz, to join them. Tobias is no environmentalist (he drives a BMW 7 Series), but he shared Uli’s frustration with bulky modern cars and talks disparagingly of SUVs as “tractors”. Before Loremo, Tobias’s company held contracts with Audi and BMW, designed mobile phones and worked on kitchen appliances for Bosch and Siemens.