Land Rover reduces CO2

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The Evoque might be getting all the attention at the moment, but Land Rover is also reducing the emissions of its Discovery and Range Rover Sport models.

Anyone who has ever driven a Discovery or Range Rover Sport over a serious off-road course will know how incredibly capable these vehicles are in such conditions, and their engineering for such tasks doesn’t make it easy to achieve low emissions.

Nevertheless, Land Rover has reduced the emissions of the 3.0-litre SDV6 diesel Discovery and Range Rover Sport from 244 and 243 g/km respectively to 230 g/km CO2.

This corresponds to a small improvement in combined fuel economy from 30.7 mpg to 32.1 mpg. At the same time, power is up, from 245 hp to 256 hp.

These improvements are mainly due to a new ZF 8-speed automatic gearbox mated to a revised EU5 3.0-litre SDV6 diesel engine.

The new ZF transmission provides closer ratios and a greater overall ratio spread, while the higher overdrive ratio reduces fuel consumption and CO2 emissions. Efficiency is further improved by the internal mechanical layout which means that no more than two internal clutches are open at any one time.

The hydraulic actuating system is also more efficient, the hydraulic pump drawing less energy from the engine. The torque converter is calibrated to lock-up at lower speeds and operating temperature, reducing fuel consumption and taking advantage of the 3.0-litre diesel engine’s huge low-end torque.

Transmission Idle Control selects neutral when the car is stationary and the engine idling in drive, reducing drag on the engine and saving fuel.

The transmission takes just 200 milliseconds to change gear. Driver Type Detection monitors driver inputs and the car’s systems to optimise the response of the gearbox to the driver’s style, while Curve Detection makes sure the gearbox avoids unwanted upshifts and holds on to the same gear when taking a sequence of bends.

The gearbox also monitors the driver’s use of the brake together with the rate of deceleration to set up the correct gear for entry and exit to the corner. The transmission does not have to change to a lower gear sequentially and can skip up to six ratios if necessary, for much faster response when preparing to overtake.

Driver controls include steering wheel paddles as standard enabling the driver to take control of gear shifting manually. The CommandShift lever is replaced by a rotary knob for selecting park, reverse, neutral, drive or sport modes, the last of these optimising the gearbox response times for maximum acceleration, improved response and sharper upshifts. The selector knob is flush with the centre console when the ignition is switched off, rising up when it is switched on. To avoid confusion, the Terrain Response Rotary Switch is replaced by a new Terrain Response Optimisation Switch.

The engine is also more efficient, having two turbochargers, working in parallel sequence. Normally, a turbocharger, although providing more power, also requires pressure from the exhaust, creating pumping losses in the engine and increasing fuel consumption, but the Land Rover system aims to minimise this.

The parallel sequential turbocharging system of the 3.0-litre diesel makes use of its larger, primary turbo most of the time. The smaller secondary turbo remains dormant when higher power is not required, reducing pumping losses and consequently, fuel consumption.

The third generation common rail injection system with piezo injectors and fuel metering also makes a substantial contribution to fuel economy.

Engines have also been optimised for low-end torque as well as economy, making it possible to activate the lock-up clutch of the automatic transmission at lower speed. This reduces ‘slip’ in the hydraulic torque converter, improving both fuel consumption and CO2 emissions. The higher torque at lower rpm also enables longer gearing for more economical cruising.

At standstill, the idle speed of the V6 is a low 710rpm, using the minimum of fuel without compromising refinement. An Intelligent Power Management System includes Smart Regenerative Charging, so whenever possible the alternator charges the battery when it is most economical to do so, such as when the car is coasting rather than accelerating.

Aerodynamic features at the front end such as the lower chin spoiler and front wheel deflectors help to reduce drag by increasing underfloor airflow. The air conditioning pump is driven through a clutch which disengages when the air conditioning is not in use, reducing parasitic losses and delivering improvements in fuel consumption and CO2 emissions.

Maximum torque is available from only 2,000rpm and the new twin-turbocharger 3.0-litre diesel delivers 500Nm in only 500 milliseconds from idle, meaning drivers have instantaneous access to 95 percent of maximum torque.

All EU5 SDV6 models are equipped with a diesel particulate filter (DPF) and have an advanced EGR system to reduce NOx.

Both models are available in the UK from October 2011; the 2012 model year Discovery 4 starts at £37,995, and the 2012 model year Range Rover Sport starts at £48,795.

If you want a lower emission Range Rover, the Evoque is coming soon, with emissions starting from just 130 g/km CO2. After that, we’re looking forward to the 89 g/km CO2 Range Rover Sport prototype coming to market.