 IT HaS been 125 years since the first car was built. But what is not often remembered is that, in the first 20 years of the development of the automobile, a debate raged - how would these new-fangled motorised vehicles that were set to replace the horse-drawn carriage be powered? The late 19th-century development of the car was in flux until the electric car was supplanted by the efficiency and ease of use of the internal combustion engine in the early 20th century. Once the manufacturers and buyers reached this consensus, roads and service stations were built, and oil became one of the world's most important commodities.  Fast forward a century and the flux over the future shape of motoring has returned with a vengeance. Pollution, traffic congestion, oil wars and the skyrocketing price of petrol - not to mention the cost of governments around the world cracking down on carbon-belching gas guzzlers - has driven customers and manufacturers alike to search for a better way. add to this expectation that, as the middle classes expand in India, China and South america, the number of cars on the world's roads is projected to more than double to 1.6 billion by 2050.  Just for comparison, the world's existing 750 million cars burned up about 60 per cent of all the oil produced in 2010. If you make even the most rudimentary calculation weighing the balance between rapidly diminishing global oil reserves and rampant demand for the autonomy of a car, the problem is clear.  In Berlin last week, a potential solution - or rather a whole range of them - was on display. The Challenge Bibendum, an annual event that takes place across the globe, brings together a host of car, truck and even motorised bike manufacturers - from Germany, France, the US and Japan - to show off the latest in future car technology, all aimed at reducing CO2 emissions and petrol consumption.  Hosted by the French tyre manufacturer Michelin, there were 280 different vehicles on show at the event, hosted at Berlin's historic Templehof airport. These included a whole panoply of ways of getting around, from electric tuk-tuks, to fuel cell-powered motorised bikes - where the cells can be used to power light and cookery facilities when camping - to massive biodiesel-powered hybrid engine lorries. There was even a tiny but largely unfeasible - at least for Scotland - prototype solar-powered vehicle.  When it comes to energy-conserving, emission-friendly cars, most people think about hybrids, vehicles that combine internal combustion engines and electric drive-trains. The most common and best-selling of these is the Toyota Prius. Until quite recently, the high costs of hybrids for consumers have often outweighed the benefits. Prices have come down considerably as more drivers seek to show off their green credentials. a typical Prius now costs around GBP20,000, with a GBP5,000 discount available from the UK government. Yet despite the benefits of hybrids - most of which come from zero road tax incentives - some newer combustion engines, if driven carefully, easily compete with hybrids on fuel use and emissions.  But if they haven't already got some form of hybrid engine vehicle in production, most manufacturers have joined in the hybrid craze, including Honda, Lexus, Ford, Volvo and Vauxhall. In autumn, even Porsche will bring out its next generation Panamera in the UK, priced from GBP85,000.  The technology is hardly straightforward. There are micro and "mild" hybrids, which both increase the fuel efficiency of petrol engines with "start-stop" technology where the engine shuts off when not in use and which also use the energy given off by applying the brakes to charge batteries. There is a wide range of "full" hybrids like the Prius, but there are also the next generation of "plug-in" or parallel hybrids which extend the range the vehicle can be powered by an electric battery from about 1.2 miles (2km) to 12 miles (20km). Toyota will bring this to market in 2012.  In Berlin, the real buzz of the show came from the next step in green motoring, the pure electric vehicles (EVs), which have no engine in them whatsoever - no exhaust, no spark plugs, pistons, hoses nor belts.  The first mass-market full electric car is the Nissan Leaf. But for the more discerning motor-head, there is the US/British electric supercar, the Tesla Roadster. The Tesla has been on the market since 2008. Strong sales in the US and Europe - about 1,500 by the start of the year - demonstrate how an ambitious and well-funded start-up company can move faster than traditional car makers to bring cutting-edge technology to market.  Earlier this month, drivers took a Tesla 874 miles from Land's End to John o' Groats using a new network of electric car plug-in stations installed at hotels and tourist destination, overturning preconceptions that EVs are unsuited to long distances. In Scotland, the low-slung roadster stopped and recharged at the Macdonald aviemore resort as well as a Marriot in Kirknewton outside of Edinburgh where the points are installed. The drivers estimated the trip cost them GBP20 for electricity - albeit the 2.5 roadster will set you back around GBP100,000.  In Berlin, the Porsche team was causing a stir with its prototype, all-electric Boxster-E. Unlike other electric cars coming to the market, the Porsche makes no concession to the need for smaller, lighter bodies or thinner tyres.  as a test drive was on offer, I took it.  The Boxster-E has the same deep, bottom hugging seats and sleek looks of the traditional Porsche. The driver, Guenther, a Porsche engineer, moved the machine slowly out of the display area to the former Templehof runway where the test drives were taking place.  "Can you show me what it can do?" I asked. Guenther merely smirked while my head was thrown back as he pressed the accelerator. He explained the Boxster-E goes from 0-60 (zero to 100km per hour) in 9.55 seconds. Yet as we powered along the runway-turned test track, the most notable thing was the complete silence of the engine. Oddly, while the European Union is currently putting rules in place to reduce the noise made by car tyres, car manufacturers are concerned about the lack of noise made by EVs, with a number of manufacturers considering whether or not they should install noise makers. Guenther, who like many sports car enthusiasts enjoys the roar of the engine, says another electric prototype Porsche already has a sound generator.  Yet the main trouble with electric vehicles is that batteries (the latest tend to use lithium ion fuel cells) are heavy, which shortens the distance they can drive - and expensive.  Igo Besselink, a research engineer at the Eindhoven University of Technology, was displaying a Volkswagen Lupo that had been converted to an electric car. He was proud of the fact the four-seater could drive for 102 miles (170km) without need for charging the battery but admitted its range was still a problem. "Most will not go more than that," he said. "It's fine for day-to-day driving but you can't make it to south of France on holiday. Sorry."  David Tonery, the founder of the sole Scottish company at the exhibition in Berlin, said battery-powered electric vehicles would only become feasible when there was a "great leap forward" in battery technology. Tonery's firm, Oxy-Gen Combustion, is developing an engine that dramatically reduces fuel consumption. He is one of a growing section of the industry that believes combustion engine technology still has a long way to go in terms of becoming more efficient, easier to use and still cheap to produce.  Dr Thomas Weber, of Mercedes-Benz manufacturer Daimler, says unequivocally that while the future of the automobile is electric, hybrids are currently an "indispensable option for the future"  "They are needed, first of all, simply because electric drive units will not initially be able to be produced in required quantities and at viable costs in the high volume segment - and because the necessary infrastructure is still lacking.  "Over the next few decades the quality of the internal combustion engines will, therefore, continue to determine how much fuel is in fact saved and what levels of emission can thereby be prevented."  and there are serious concerns that if everyone bought an electric Nissan Leaf tomorrow, the UK's electricity infrastructure - which is still largely powered by coal anyway and thus prone to CO2 emissions - would collapse. This is why hydrogen is now being seriously considered as the "sustainable travel" endgame by many manufacturers.  The trouble with hydrogen, which is used in fuel cells to power electric vehicles, is that the technology is not quite there yet as a viable alternative. There are hydrogen fuel cell cars on the market, most of which are in California and Germany. Daimler's Mercedes-Benz F-Cell was one of the first to be manufactured in a small series, but other manufacturers, including Ford and Renault, have discontinued research in this area.  Many hydrogen fuel cell designs require rare, and expensive, substances such as platinum in order to work properly. Researchers are also working on ways to produce and store hydrogen that do not require fossil fuels. One answer may come from using wind energy to produce synthetic methane - which can be used to safely store hydrogen. But these plans are still works in progress. add to this predictions that the cost of installing enough fuel points to service a million fuel cell vehicles in Europe would cost ???3 billion (GBP2.5bn), and the challenge looks daunting.  although most car makers are working on a range of options for motoring, the only agreement to be found on the way people will d 