The fourth generation Discovery 4 was launched in 2009, and went on sale in the United Kingdom on 1 September. Compared with the 2.7 litre TDV6 engine, which continues to be offered on the Discovery 4, the new TDV6 3.0 litre twin turbo diesel engine delivers a 9% fuel economy improvement (EU combined cycle) and 10% lower CO2 emissions, at the same time as increasing power by 28% to 241 bhp (180 kW); torque increases 36% to 600 N·m (440 lb·ft). The results include a 060 mph time of 9.0 seconds, (0100 km/h in 9.6 seconds), a 24% improvement over the 2.7 litre model. The new engine has been optimised for low-end torque as well as economy, making it possible to activate the lock-up clutch of the ZF HP-28 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 engine speeds also enables longer gearing for more economical cruising.
Land Rover's engineers have also transformed the on-road ride, handling and off-road capabilities. The changes include new suspension components, revised steering, larger brakes, improved traction control, and enhancements to the Terrain Response system, which helps optimise the vehicle for different on-road or off-road driving situations.
The exterior design of the Land Rover Discovery 4 has been updated, most obviously with smoother and simpler surfaces at the front, including a new, more aerodynamic bumper. Aerodynamic changes to the front end, with the revised front lower chin spoiler and new front wheel deflectors, help to reduce drag by increasing underfloor airflow. The new lights include LED technology front and rear. The front headlights include High Beam Assist, switching on or off, as conditions require.
The interior has been redesigned, with a transformed dash, centre console and new seats.
The Land Rover Discovery 4 incorporates other energy saving features. At standstill, the idle speed of the V6 has been reduced from 750 rpm to 710 rpm, giving a fuel saving 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. The new 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.
Admist these revolutionary innovations, the LR4 has also been subjected towards some critisism from old time Discovery fans around the world for being more of a "Macy's Parking Lot Vehicle" rather then a "real" Land Rover. For example, the LR4 doesn't utilize a classic oil plug in the bottom of the oil pan as do most every car and truck. The only way to change the oil in an LR4 is to have a Land Rover Dealership use a special device to "vacuum" the oil out of the engine. This means that if you follow the 3k-5k mileage timeline for oil changes, and plan on driving the car to 100k miles, plan on a minimum of 20 visits to the dealer, not including additional maintianence necessary.
A 2.7 litre commercial version, the Discovery 4 XS Commercial, is offered in the United Kingdom. It has N1 Light Commercial 4x4 Vehicle status, which reduces the annual cost of the vehicle excise duty to £125, compared with £405 (increasing to £950 in April 2010), payable for the normal 2.7 litre Discovery 4.
5.0l V8 petrol2009 (MY2010)-4,999 cc (4.999 L; 305.1 cu in) V8 16v (AJ133)375 PS (276 kW; 370 hp)@6500, 510 N·m (376 lb·ft)@3500
2.7l TDV62009-2,720 cc (2.72 L; 166 cu in) V6 twin turbo (Ford AJD-V6/PSA DT17)191 PS (140 kW; 188 hp)@4000, 440 N·m (325 lb·ft)@1900
3.0l TDV62009 (MY2010)-2,993 cc (2.993 L; 182.6 cu in) V6 twin turbo (Ford AJD-V6/PSA DT17)244.5 PS (180 kW; 241 hp)@4000, 600 N·m (443 lb·ft)@2000