Google+

BBC Autos

Twizy RenaultSport F1: Little yellow devil

HIDE CAPTION

Electric cars sound a bit crummy, right? The Twizy RenaultSport F1 doesn’t.

In fact, the nanosecond the Renault engineer prods the little silver starter nodule, I briefly wonder if I’m about to shoot upwards rather than forwards. A pump whirs, some other bit of costly unobtainium emits an escalating whistle like a demented kettle and the whole thing pulses with palpable energy. It’s brilliant.

Rather than Doc Brown’s flux capacitor, though, I have the KERS from a Renault F1 engine sitting barely inches from my backside. KERS, as you know, stands for Kinetic Energy Recovery System, a fiendish box of tricks that arrived in F1 in 2009, as the sport decided it was high time it cleaned up its act. Energy previously wasted during deceleration or braking would now be harvested, stored in batteries, then redeployed by the drivers in slugs of up to 80bhp, for around six seconds per lap on average. Once the teams had stopped accidentally electrocuting mechanics – it happened at BMW Sauber – it all started to go rather well.

The Twizy RS F1 is basically KERS on wheels, as RenaultSport F1’s marketing operations manager Tarik Ait Said explains: “A lot of the current technology transfer from F1 to road cars is invisible. We wanted to show how KERS, which still confuses some people, could be applied to a road car. What better way to showcase it than by harnessing it to an electric engine?” The upshot is a Twizy with almost 100bhp, capable of running with a Megane RS 265 to 62mph – TG’s kind of showcase.

The system consists of three main components: an electric motor generator unit, which is hooked up directly to a driveshaft, a KERS control unit and a lithium-ion battery pack. Lifted almost entirely from the Renault F1 engine – 2011 spec, to be specific – it boosts the regular Twizy’s 17bhp power output to 97bhp. In effect, this is a twin-engine Twizy, and the latest in an esteemed line of eccentric yet weirdly relevant Renault concepts.

Creating an F1 battery-powered Twizy was not without its engineering challenges. For example, KERS cuts in seamlessly on an F1 car from around 60mph, rather than having to do its thing from a standing start. That meant rewriting the software algorithms and reworking the electronics. Fortunately, the standard Twizy chassis – developed by RenaultSport – was actually overengineered, so the suspension is standard. The wheels come from the Formula Renault 2.0 single-seater.

Packaging it all meant junking the regular Twizy’s rear seat, though. Tucked away under a Plexiglas screen is the 10cm-diameter cylinder that hides the main KERS motor, with the power control unit nestling close behind it, which converts the energy. All of this, plus the additional battery pack, generates a lot of heat, so there’s extra visible plumbing here too, liquid cooling supplied via a set of blue pipes. There’s a radiator, a pair of fans, and if you look closely, you’ll spot a sliver of grille in the rear bodywork. That’s if you can tear yourself away from the front wing and rear diffuser, both of which have as much to do with generating downforce as Igglepiggle but still look great.

More significant is the F1’s specific gearset, which has the tricky job of harnessing the two motors and ensuring that the Twizy F1 doesn’t simply fizz, pop and explode on the spot. The standard Twizy’s motor usually spins at 7,500rpm, though it can run as high as 10,000rpm; the KERS motor operates at a huge 36,000rpm. A reducer gear ratio means they talk to each other. The existing Twizy batteries and motor sit under the driver’s seat, as usual.

If the regular Twizy is oddball enough to climb into and operate, the F1 cranks up the comedy a few notches. The steering wheel is taken from the Formula Renault 3.5 single-seater, so it’s really more of a portable directional computer. Twin LED displays in its centre show the level of charge in the main battery and the KERS, as well as oil pressure and water temperature. Two rotary knobs govern the car’s Recovery mode, siphoning off energy from the Twizy’s main motor and storing it, and there’s also a Boost mode, which lets the driver redeploy it in 13bhp increments up to a max of 80bhp. The glovebox is now full of sockets and ports, having effectively become the communications centre.

Cue the whistle and whir. It’s a distinctly unusual sensation compared to the near silence that greets the operator of a regular Twizy. There’s clearly some energy creation going on somewhere, but, as with all electric cars, it feels more like it’s in the ether than in your hands. RenaultSport F1 has arranged a drag race between me in the Twizy F1 and a test driver armed with a Megane RS 265. Pull back on those carbon paddles, and the KERS is locked and loaded. Simply release the paddles and hang on. There’s a beat, and then I rocket forward on a fabulous whoomph of torque. There’s absolutely no skill required, and for the first part of the run I’m definitively outpacing the Megane. He breaches the timing beam first, although my data-logged 0–62mph time of 7.6secs is still pretty good.

“You know,” Ait Said says, “F1 is a remarkable development accelerator. If you want to know which way to go with a technology, give it to an F1 team. They’ll tell you a week later.” Which begs the question: are we likely to see KERS – an integral part of the LaFerrari and McLaren P1, remember – in the next-generation Megane Sport? It’s possible, though Ait Said won’t be drawn. “I definitely want to put the 2014 F1 V6 turbo into it, though,” he says, smiling. “Imagine that…”

This story originally appeared in the November 2013 issue of Top Gear magazine.