To celebrate its 50th anniversary, Caterham has unveiled the most powerful Seven ever; the X330 - a one-off supercharged model boasting a mind-boggling power-to-weight ratio of 600bhp per tonne.

The stealthy, matt black concept is based around the range-topping CSR Superlight, but the addition of a supercharger to the four-cylinder 2.3 litre Ford Duratec engine increases power massively from 260 to 330bhp - as the name suggests.

That means the X330's equivalent power-to-weight ratio puts it ahead of the Bugatti Veyron (521bhp per tonne) and the McLaren F1 (559bhp).

The near 35% power hike is achieved by a Rotrex C30-94 supercharger, which provides a boost characteristic that rises linearly with engine speed. In other words, although the X330’s punch is greater at higher revs and speed, low-speed driveability isn't compromised thanks to an exceptional torque curve with over 221 lb-ft from 5500 to 7500rpm - 20 lb-ft more than the CSR260.

As the X330 is an engineering test bed it is envisaged that some of the concepts will eventually find their way into production. To begin with the X330 will spearhead the British firm's R&D into bioethanol power in the coming months as it seeks to assess the viability of alternative fuel sources in road and race applications and cement a further 50 years of history for the legendary Seven.

In keeping with the Seven ethos of "adding lightness", the extremity of the X330 doesn’t stop at moving parts. Lighter gauge steel is used in the trellis-style chassis and the use of new lightweight wheels together with an abundant use of carbon fibre for the bodywork all adds to the stealth appearance of this perfect 50th birthday present.

Italian supercar maker Lamborghini will showcase the new Gallardo Superleggera coupe at the Geneva Motor Show in March. Thanks to increased power (an additional 10 hp) and a 220-pound reduction in weight (154 pounds for the U.S. model), the new range-topping Superleggera is faster and more agile than the regular model.

The Superleggera needs only 3.8 seconds to go from 0 to 62 mph — 0.2 seconds less than the basic Gallardo. The Lamborghini Gallardo Superleggera comes with robotized mechanical e-gear as standard; a sports package including shock absorbers; and special suede-covered steering wheel.

The car's engine is the latest version of Lamborghini's well-known 4,961 cc V10. 530 hp is achieved in 8,000 rpm.

Lamborghini engineers decreased the Lamborghini Gallardo's already low weight using advanced materials. The engine hood is made of visible carbon fiber and plastic, a type of material that guarantees lightness and also shows off the magnificent V10.

The rear diffuser and underbody covering, the rearview mirrors, door panels and the central tunnel's covering are also made of carbon fiber. Further reductions in weight were achieved by replacing certain glass surfaces with clear plastic. For the interior, monocoque carbon fiber sports seats covered in Alcantara are offered.

A new round of spy photos of the recently-spotted BMW Z-car prototype raise questions about its true identity. First believed to be a prototype for the SL-fighting Z9, it now appears this prototype test car actually be the next Z4.

Behold the first shots of BMW's new convertible prototype caught with its top down. It probably sounded like a good idea at the time, but the temptation of a top-down test run came back to bite these BMW engineers when our photographer caught the car stuck in traffic and pounced on them at a stop light. The close-ups didn't yield any meaningful dashboard details thanks to the interior's protective covering and the flailing arms of the engineers, but spies did manage to see some details that suggest this might actually be a Z4 after all, and not the Z9.

First off, we have been told that the MX-5 Miata you see driving in front of this prototype was no mere traffic coincidence. Our photographer reports that the Miata appeared to be part of the test group throughout the afternoon. It seemed to be on hand for comparison purposes–which would clearly point to the Z4 replacement as the likely I.D. of this prototype. These topless photos also reveal that this test car had cloth seats — something that would never be found on a car in the Z9's stratosphere — once again strengthening the Z4 case.

The stowed top also gives a more revealing look at the rear deck just behind the car's roll-hoops, and cut lines suggest that this could be a conventional soft top, and not the folding tin-top destined for the range-topping Z9. We can't know for sure until we see the folding top in action, but it all looks quite suspicious to us.

As for the apparent size discrepancy between this prototype and the Z4, it could largely due to some ingenious camouflage. A closer look at some of the space between the outer camouflage and the true body that lies beneath suggests that the camo shell may sit several inches above the real body panels in many places. The hood camouflage, for example, easily sits 4- to 6-inches above the true hood-line, at the cowl. Strategic placement of such misleading dimensional cues can be very effective in playing tricks on our eyes and perceptions. There may be a significantly more svelte and petit car under all of that armor. And the next-gen Z4 could logically be upsized a bit, if BMW plans to bring a smaller Z2 into its lineup by decade's-end, as rumors suggest.

These latest open-top shots of this Z-car prototype may raise more questions than they answer, but they give us a better sense of what lies at the heart of these mysterious test cars. Our first look into the cockpit area suggests that this is a car aimed at a more mainstream part of the market, which has us beginning to lean back toward the Z4.

When Honda unveiled the Advanced Sports Car Concept earlier this year, it said the vehicle was a direct preview of the 2008 Acura NSX. Typically automakers don't say which future production cars ambiguously named concepts are supposed to represent, but Honda officials had no problem disclosing their intentions for this project.

Now it appears the car might be headed back to the drawing board.

Although it wasn't slammed by the automotive press or enthusiasts, the concept didn't get rave reviews, either. It turns out Honda executives were hoping for something more breathtaking, too. As a result, they've asked the design team to rethink their plans, according to a report by Winding Road magazine.

While the basic proportions, V10 engine, and all-wheel-drive will stay, the rest of the package will likely change before production begins in early 2008. Look for the production version of the new NSX will arrive at the Tokyo Motor Show this fall.

Austrian motorcycle builder KTM today released photos of a full-scale prototype of its new X-Bow (crossbow) roadster. The 1500-pound car has a four-cylinder Audi engine offering 220 horsepower in the base model, and a potential 300 horsepower in a more expensive variant. A choice of either a six-speed manual or DSG gearbox will be given. KTM says the base X-Bow will hit 62 mph in 3.9 seconds.

The X-Bow has no windshield, and instead will come with specially designed helmets, intended to offer shelter from the elements rather than full crash protection.

After its debut in Geneva, 100 units will be manufactured in-house by Italian racing car specialists Dallara and sold by KTM. The price for the basic version will be around 40,000 euros.

If all goes well, KTM plans further small series productions of the car. This production will take place in Austria and begin in 2008. KTM is working on the basis of a projected 500 units per year. The decision concerning production will be made at the end of April 2007.

Maserati's GT is back, with a sleek new body and a new emphasis on comfort and refinement. The rear-drive coupe is powered by a 400bhp 4.2-litre V8 engine, so it won't be short of performance, but it's a car in the GT tradition of long-distance tourers rather than a full-on sports car.

On sale later this year after its unveiling at next month's Geneva show, the GranTurismo is built on a shortened version of the Quattroporte's chassis, and the styling by Pininfarina has echoes of the larger car's. The Italian design house's founder, Pinin Farina himself, designed Maserati's first great road car, the A6 of 1947.

The new GranTurismo is larger than the outgoing Coupe, with room in the back for two adults, but only two doors. The gearbox is automatic. Open-top and high-performance versions are expected to follow.

German tuning firm Lumma-Design has put together a tuning kit for the BMW M5 sedan. It features extensive body modifications, including carbon fiber roof, trunk, and hood; new front and rear aprons; a widebody kit with larger fenders; new side skirts; and more.

It also features 21-inch wheels, extra-wide Yokohama tires, a performance exhaust system, extensive chassis tuning, upgraded H&R suspension, and more.

Most notably, the car's V10 engine has been pushed from a stock 500 horsepower up to 560 hp.