Biofuel: Gentle green giant

This 2009 Chevrolet Silverado, a petrol-electric hybrid, is environmentally friendly. Photo / Supplied

With the Hamilton 400 V8 Supercar circus next week, and trucks like the Chevrolet Silverado still selling in the US, you might be forgiven for thinking GM and its Australian branch aren't treating global warming seriously.

But both are taking a walk on the mild side. The V8 Supercars are fired by E85 biofuel, while this mighty

truck is a petrol-electric hybrid - GM's answer to Americans who would like a big truck with a more frugal fuel bill.

Badged as a Chevrolet, the 6.0-litre, V8 engine uses active fuel management to cut cylinders when it's under light load - as now fitted standard to Holden's V8 Commodores. It also uses auto stop to cut the engine when the ute is standing still, regenerative braking to keep the battery that is mounted beneath the rear seat charged and reduce power draw from the mechanical powerplant, low-rolling resistance tyres and aerodynamic mods like a deeper front air dam.

GM says the two-mode hybrid was developed initially for transit buses in North America and Europe, then scaled down for trucks like this. The set-up is shared with the likes of the Chevy Tahoe, Cadillac Escalade and Dodge Durango and was developed alongside Chrysler, BMW and Mercedes-Benz.

The system uses two electric motors and four fixed gears. Two modes operate according to load, one used at low speeds and the other on highway driving, when active fuel management shuts down four cylinders under light throttle settings.

The Silverado can drive using electric propulsion alone at speeds of up to 48km/h, even when loaded or towing a trailer. With all guns blazing, there's 247kW and almost 500Nm on tap from a truck that will deliver an 11.7-litre/100km thirst, city or highway. That's around 40 per cent better than the standard model around town, 25 per cent better overall and rather good for a 5.8m, 2.6-tonne behemoth.

Vehicles like this are just part of a broad suite of fuel-saving developments, in the short term aimed at sending the right message and re-educating the American consumer.

Meanwhile, Kiwis will get their own re-education when they see how fast a V8 Supercar can lap the Hamilton street course with E85 biofuel in the tank. And thanks to Holden, two lucky Herald on Sunday readers will be able to take a mate to watch them in action.

We have two double passes to the Hamilton 400 to give away, each valued at $200, including a three-day grandstand and pit pass.

Simply send an email to motoring@heraldonsunday.co.nz by April 8 to go in the draw.