It's a horrible cliche, but knowing where to start with the VW XL1 is real challenge. Therefore you can read
some driving impressions
separately and here we'll outline the tech of this incredible little car.
Camera replace mirrors on aero grounds
The XL1 represents a decade of development of Ferdinand Piech's vision for a usable car capable of 1l/100km (282mpg). This began with the L1 of 2002; by the time the 2009 L1 was revealed, work was already underway on the production XL1.
This is really an engineer's car, and it's therefore hard to avoid a comparison with original Honda Insight. Both employ a methodical and innovative approach to efficiency, rejecting the conventional dullness of hybrid vehicles to wide acclaim. Whether you will ever be able to buy an XL1 for £3,000 though, is another matter...
Surprisingly, the Porsche 917 is another vehicle the XL1 has ties with. Ferdinand Piech was involved with both projects, and there are links between the two; the Porsche was one of the first cars to use magnesium wheels, as does the XL1. The rear-mounted fans in both are similar and the overall proportions are not dissimilar. Unsurprisingly, the Porsche Le Mans legend isn't mentioned in the press pack...
Entirely smooth front helps 0.189cD
With around 40 per cent of a car's weight typically accounted for by the body, VW had a project goal of significantly reducing this for the XL1. The carbon fibre reinforced poylmer (CRFP) monocoque is both a safety cell and a supporting structure; its 89.5kg total weight is an important contributor to the XL1's 795kg kerbweight. Aluminium subframes are attached to cradle the battery pack at the front and the electric motor/diesel at the rear. CRFP is again used for the body panels to further reduce mass. Consequently, the XL1's body is now only 29 per cent of the overall weight, at 230kg. The drivetrain contributes another 227kg, the chassis 153kg and the final 185kg is comprised of equipment and electronics. The overall weight distribution is 40:60 front:rear
Dash is clad in carbon film; every little helps!
VW designer Peter Wouda rebukes the official claim that the XL1's appearance is based on a penguin, whose drag coefficient is, according to VW, an amazing 0.03. "That's marketing bulls**t. I was inspired by sharks." That's settled then.
But that does explain the aggressive yet smooth front end and narrow rear, with every surface made as flush as possible. The rear windscreen is steeply raked, the underside flat and the rear wheels covered to boost the XL1's aerodynamics. The overall result is an astonishing drag co-efficient of 0.189.
The windows are made from polycarbonate, which is around a third lighter than glass. On top of the weight saving, the flexibility of polycarbonate gave the designers more freedom with the glasshouse. It also means that side airbags aren't necessary as it will not shatter like regular glass.
The meticulous attention to removing unnecessary weight continues inside. The dash is made from recycled wood pulp, mounted in a magnesium carrier and then trimmed in a carbon film. Driver and passenger both sit in carbon fibre seats without conventional height and backrest adjustment, with each one weighing just 11.6kg.
Slatted covers cool carbon-ceramic brakes
It's a shock the first time the guys from VW dry-steer the XL1; the 115/85/R15 tyres look to have been sourced from a bike shop. They have also been specifically designed for the XL1 with Michelin. Might be worth phoning Kwik-Fit in advance for a new set...
The magnesium wheels are covered by slatted trims to aid cooling of the carbon-ceramic brakes. They are used to further reduce unsprung mass and each is 280mm in diameter.
Powertrain and transmission
In layman's terms, the XL1's 800cc two-cylinder engine is half of the 1.6-litre diesel found in something like a Golf Bluemotion and produces 50hp. With the electric motor's assistance, total power is 67hp. It is supplied by a lithium-ion battery pack rated at 5.5kW/h, which is water-cooled and cased in the same carbon fibre reinforced polymer as used on the XL1's tub and body. In total, the battery pack weighs 68kg.
Weight saving here? Yep, DSG uses magnesium
The XL1 is a parallel hybrid, meaning it can run on either power source or both. The electric-only range is 50km (31 miles) with a top speed of 70mph. At 1l/100km (282mpg, below the official claimed figure), a range of 1,000km is theoretically possible with a 10-litre tank. Emissions are rated at 21g/km of CO2. A full battery charge takes between 90 and 160 minutes depending on the supply, plus regenerative braking also restores charge.
The DSG is the same as used in other VW group models, but with magnesium components rather than aluminium to save weight.