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Sunday, 17 March 2013

VW Group Moves On From Conquering Speed, Conquers Economy

2013/4 VW XL1
VW is on-and-off the largest car company in the world. Or rather VW Group (Volkswagen AG or VAG) is. If VW were your boss, VAG would be your boss's boss. It owns no fewer than twelve brands, those being Audi, Bentley, Bugatti, Ducati [motorbikes], Lamborghini, MAN [lorries], Porsche, Scania [also lorries], SEAT, Škoda, Volkswagen Commercial Vehicles and VW itself. With that list of brands you get some serious firepower, and the mighty VAG (stop sniggering) has flexed its muscles once again to give the world an amazing piece of engineering you can actually buy*. After the 268mph Bugatti Veyron Super Sport conquered the speed world, VW has realised a ten-year ambition to conquer economy cars with this, the 313mpg XL1.

*well, word on the street is that they'll lease this one.

The above fuel economy figure is not a typo. Using UK gallons, it really does get three hundred and thirteen MPG, or to put it VW's way 0.9L/100km. This is the realisation of an idea first tested over a decade ago with the little black motorised suppository known as the VW 1L. The 1+1 seater was driven from Wolfsburg to Hamburg as part of an April 2002 stockholder's meeting by big boss and master of VAG (I said stop it!) Ferdinant Piëch. It was streamlined to the point where it had a flat underside, hidden rear wheels (plus disc-shaped covers on the front ones), used little cameras instead of mirrors and had almost no styling and a fighter jet-style bubble canopy. Its tiny dimensions of 3470x1250x1100mm (LxWxH) combined with this streamlining to give a staggering drag coefficient of just 0.159. For some perspective, a Prius's Cd is 0.24, while a Nissan GT-R or Toyota GT86 manages 0.27 and an average family car 0.3-0.4. The lowest-drag car on sale today is the Mercedes-Benz CLA at 0.23, and almost no car has ever gone below 0.2 Cd, with only the similarly-sized General Motors EV1 getting close to the VW 1L at 0.195 (interestingly, the Tatra 77A from 1935 held the record for lowest drag until the EV1 appeared). Low drag improves fuel economy, if that wasn't obvious yet, and sure enough it managed 0.99 litres per 100km.

Power was never going to be from some four-cylinder turbo engine, but the 299cc one-cylinder diesel is pretty limp by most standards. Still, only what's necessary; power peaked at a mere 8.4bhp, which was sent from the mid-mounted engine to the rear wheels via a 6-speed clutchless manual that combined automatic and manual gearbox bits for maximum efficiency. That 8.4bhp was adequate for propelling a car which only weighed 290kg (plus fuel and driver), which is less than half the weight of an original Mini. This was achieved by putting a carbon fibre body onto a magnesium-alloy subframe, as well as other lightweight parts including carbon fibre wheels, aluminium brakes, titanium wheel hubs and ceramic wheel bearings, not to mention the tiny engine, optimised gearbox and minimal interior. Because the fuel tank itself contains more than a litre, the 1L could go up to 404 miles (650km) on a tank. Slowly.

The idea was developed over time and Piëch said in 2007 that the car would be available to buy at the end of the decade... which it wasn't. In 2009 it was given a restyle and made into the 'L1', which looks much like the car you see up top but retaining the side-hinged canopy and tandem seating. The restyle also increased drag to 0.195 Cd thanks to being slightly bigger, at 3813x1200x1143mm, while weight increased to 381kg, a jump of 91, thanks mostly to its beefier powertrain. Because you can't sell an eight-horsepower car when you're the biggest car maker in the land, it gained a second cylinder, a turbo and a hybrid system, because hybrids were all the rage, and in some places still are. Actually, the reason for the hybrid system is to stretch the range out a little bit more, presumably because it could no longer do 1L/100km without hybrid help providing an electricity-only option for short distances. It also adds 14bhp to what's either 27bhp or 39bhp depending on whether you've got the engine in Eco or Sport mode. The extra power regardless of its source proved capable of propelling the L1 to 100mph, after passing 60mph 14.3 seconds since setting off.

And so, it evolved again to the car atop this post. Like the L1, the bigger 'XL1' also got half of a 1.6 TDI engine, making an 800cc two-cylinder turbo diesel, only now it makes 47bhp and 89lb/ft of torque. As well as making more power, there are specially formed piston recesses for multiple injection and individual orientation of the injection jet, while a high-precision aluminium crankcase and the balance shaft - driven by the crankshaft turning at the same speed - makes sure the 0.8 runs just as smoothly as the 1.6 from whence it came. The electric motor contributes an extra 27bhp and 14lb/ft, making totals of 68bhp and 103lb/ft. The XL1 is perhaps appropriately renamed, because it's notably bigger than its predecessors, and heavier too - at 790kg it's more than twice the weight of even the 2009 L1, due to being a lot wider in order to sit the two occupants next to eachother like in a normal car, making its 0.9L/100km all the more impressive. They haven't exactly half-arsed it on the lightweight materials though. The entire hybrid drive system weighs under 230kg. Aerodynamics of course play a big part as well, with the smooth sides - save for a couple of vents that open up when necessary - and kamm tail contributing to that all-important low drag coefficient.

Click to embiggen
At 3888x1665x1153mm, it's shorter than a Polo and lower than a Porsche Boxster, so while it's the biggest version of itself, it's still pretty diminutive in the outside world, where it will finally be. Soon-ish. Complete with butterfly-wing doors like a Ferrari Enzo, it has an improved drag coefficient over the L1, of 0.189. That will give it the lowest Cd of any production car ever. Low-resistance Michelin tyres only 145mm wide mean that the XL1 only needs 8.4bhp to cruise at a steady 62mph (100km/h), which by nice coincidence is precisely the amount of power the original car had. But how is a modern car with air conditioning and so on so light? Well, it's with lots of specialist things that won't make it cheap.

It's based around a carbon fibre tub - made in Austria using a process that can actually be used to mass-produce CFRP - and uses carbon body panels as well, which are glued together. The doors and lids are made separately, with the doors requiring high precision fitment of crash reinforcement bits and bobs as well. After all the parts are in place, all 32 exterior body panels are painted. Despite a minimally thin paint layer to save weight, a special "fleece layer" or resin film is added to the carbon parts as a cover coat, which is 50 percent lighter than what's normally used. Inside, a matte grey paint is applied as well as a matte clear coat on visible carbon parts. The body then joins the pre-fabricated floor (still with a flat underside), complete with the suspension and the drive unit. Unlike in mass production cars, all individual cockpit parts are mounted inside the vehicle superstructure. The dashboard itself consists of a moulded wood fibre material. Because that's like, SO eco.

After assembly of the drive unit, the 3.175mm thick windscreen is installed. The doors are re-installed with their exact positions and alignments already set from being fitted earlier, after which the car gets its bonnet and magnesium wheels. After installing the painted door and integrating the window mechanisms, special assembly fixtures are used to glue the polymer side windows in place. Finally, the rear-view cameras (which should become standard on all cars) are fitted in the doors.

And away you go! Off to show the world that lightness is bestness. Well, along with a tiny drag coefficient. And as little engine as possible. Volkswagen are going to make 50 cars at first, with pricing still to be announced, and after that they'll make them to order if anyone else wants one, with production not expected to surpass 1000 cars a year. Get it while it's hot!

Coefficient of drag: 0.189
Carbon fibre plays a bit part is a) making it extremely light, and b) making it quite expensive. Cheap CF isn't far away though...
Note the cameras instead of mirrors, with screens roughly where you'd naturally look. Why not do this on all cars???
Narrower rear track means enclosed rear wheels without wheel covers sticking out and spoiling the airflow anyway.

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