How VW's XL1 will make your next Golf lighter, faster and more frugal

VW will only build 250 examples of the XL1, its super-streamlined two-seater than scores a combined 314mpg thanks to its plug-in hybrid diesel engine, lightweight construction and low-drag design. Each punter will have to put up around €100,000 for the privilege of saving money on fuel – but don’t worry, because every car across the VW Group will benefit from the lessons learned, all by 2020.

Yes – VW believes plug-in hybrids are the future for propelling cars, thanks to their everyday usability and lack of range anxiety. Chief XL1 engineer Dr. Ulrich Hackenberg said: ‘All our hybrids will start up as a battery-powered car, because most journeys begin in the city. It’s quiet, and good for emissions.’ This allows the battery to discharge and accept regenerative braking at higher speeds out of town, when the internal combustion engine fires up.

Add in freewheeling capability like Porsche’s decoupling system (which eliminates engine braking when cruising to cut friction) and Dr. Hackenberg estimates a plug-in hybrid diesel Golf could score 155mpg. Of course, that figure is skewed by the EU testing procedures including electric-only running in the overall rating, but nevertheless, real-world mpg should be up in the 60s and 70s.

Not massively, because its integration has been planned from the start. The VW Group’s lightweight MQB platform, which underpins the Mk7 Golf, new Skoda Octavia, Seat Leon and Audi A3, can accept regular engine, hybrid, compressed natural gas (CNG)and fully electric drivetrains without pricey re-engineering. Meanwhile, plans are already afoot to test a tweaked XL1 powertrain in the little Up city car, estimated to sip fuel at 256mpg. So, not only can plenty of models enjoy alternative power sources, but VW’s factories don’t need retooling to accommodate each version. That saves VW’s money, and ultimately, yours too.

Aside from the carbon-neutral CNG powertrain in the Audi A3 g-tron, the VW Group is largely sticking to internal combustion power. Why no hydrogen fuel cells? Dr Hackenberg explained: ‘We are looking at hydrogen, but we are running with the pack rather than getting ahead of it. It will take at least 15-20 years before hydrogen becomes viable anyway.’
What about fighting the weight of eco tech?

It’s a big battle: the VW Golf plug-in hybrid is 200kg heavier than a conventional car due to the batteries and motor, plus extra crash structures designed to stop the battery rupturing in a side impact.

VW is looking to carbonfibre to offset weight gain, previewed in the all-carbon XL1. The clever bit is to do away with the lengthy, pricey ‘baking’ used in supercar carbon body-parts. Hackenberg says a normal carbon piece takes 10-20 hours to be finished, including the autoclave baking process. By injection moulding carbon sheets between superheated, pressurised plates, carbon pieces could be made quicker, cheaply and with less waste. Plans are also afoot to heatform super-strong polycarbonate car bodies.

Carbon tech is also being considered elsewhere in the VW Group – click here for CAR’s scoop on the next-gen (and 300kg lighter) Audi Q7 SUV.

One of the VW XL1’s true concept car features is its cameras-for-door-mirrors setup, except here VW got special permission to homologate it for road use. If the XL1’s trials are successful, it could pave the way for all cars to drop bulky mirrors. Sounds like a lot of hassle for a small win, so what’s the point?

Smaller blind spots for a start, says Hackenberg, plus less drag and wing noise (the R&D chief reckons customers simply don’t appreciate just what a hindrance wing-mirrors are on a car’s wind tunnel performance.) Also, zoom-ready cameras aid parking, while adaptive screens could monitor rear-view blind spots, and include night vision and pedestrian alerts. It’s a virtuous circle of safety, economy and downright cool looks.

The road to frugal driving is paved with good intentions – but VW is putting them into practice thanks to new EU legislation. With carmakers’average CO2 emissions mandated to drop to 95g/km by 2020, VW needs to take action beyond a few BlueMotion models.

Hackenberg says a 30% CO2 reduction can come from alternative powertrains, and another 35-40% found in aerodynamic changes, like faired-in wheels and active aerodynamics. Reduced weight is the third area to plunder improvements from.

So, expect VW to be leading the hybrid charge by the time the next Golf rolls around. Look out, Toyota – Prius-lovers might be about to jump ship.

By Ollie Kew