Land Rover announced in Detroit diesel power is coming under the hood of its 2016 Range Rover and Range Rover Sport models.

The company said the Range Rover Td6 and Range Rover Sport Td6 SUVs are expected to deliver 25 miles per gallon combined, a 32 percent improvement over the supercharged V6, and reach a high of 28 miles per gallon on the highway.

The two new luxury diesel SUVs will go on sale Fall 2015, said Land Rover.

The company explained the 3.0-liter Td6 turbocharged V6 diesel engine provides 254 horsepower and 440 pound-feet of torque at 1,750rpm; in comparison, the gasoline V6 produces its 332 pound-feet of torque at 3,500 rpm.

Land Rover stated these diesel-powered Range Rover and Range Rover Sport models are particularly well suited to towing heavy loads and off-roading where reaching maximum torque at low RPM is extremely beneficial. Similarly, the low-end torque of the Td6 allows the vehicles to deliver 0-60 acceleration times comparable to the higher horsepower V6 gasoline models. The Range Rover Sport Td6 and Range Rover Td6 accelerate from 0-60mph in 7.1 and 7.4 seconds respectively, compared to 6.9 and 7.1 seconds for gasoline V6 models, added the company.

SEE ALSO: Range Rover Hybrid LWB Debuts In China

Preliminary fuel economy figures for the Range Rover Sport and Range Rover of 22 mpg (city), 28 mpg (highway) and 25 mpg (combined) represent a 32 percent improvement over the gasoline V6 engine, said Land Rover, adding total range increases to 658 miles, a gain of 8.0 percent for the Range Rover Sport and 3.3 percent for the Range Rover.

The Td6 engine block is constructed using Compacted Graphite Iron (CGI), which has a higher tensile strength than standard grey cast iron, better fatigue strength than aluminum, and added stiffness. Its overall advantages in weight and strength mean the block can be lighter and smaller which make it compact in size, explained Land Rover. The deep-skirted, cross-bolted design and one-piece structural aluminum oil sump of the Td6 help the engine to absorb combustion noise effectively which improves refinement.

Prior to its introduction in the US, improvements have been made by the company to the Td6 helping to achieve an additional eight percent increase in overall fuel efficiency. These include the addition of a water-cooled turbocharger for maximum performance and durability at high operating temperatures; and new ball bearings, vanes and nozzles to improve efficiency.

The British manufacturer added Selective Catalytic Reduction (SCR) system uses Diesel Exhaust Fluid (DEF) to reduce NOx emissions, ensuring the Td6 achieves US LEV 3 status. The DEF is injected into the exhaust and, as the resulting mixture passes through the SCR, NOx is turned into harmless nitrogen gas. The reservoir for the DEF is located in two areas, the main one under the floor with the secondary reservoir located under the hood. Combined they hold enough fluid for approximately 10,000 miles.

This Td6 is said to include a new Low Pressure EGR system, which Land Rover stated has been critical to success of Td6 emission ratings and further improves fuel economy. Unlike traditional High Pressure EGR systems, which recirculate gases directly from the exhaust manifold to inlet manifold at high pressure, the revised design takes gases at low pressure – after the DPF filter in the exhaust pipe – and feeds them back to the turbocharger inlet. From here they pass through an intercooler, resulting in a lower peak combustion temperature.

The higher the peak combustion temperature, the more NOx is produced, so the low pressure EGR system has the effect of reducing the harmful emissions contained by exhaust gases, by lowering the peak combustion temperature and improving efficiency, explained Land Rover.

This latest Td6 diesel has been tested extensively to ensure it meets the expectations of US buyers, and these tests had been done in the U.S. according to Land Rover. Early in the development process Land Rover conducted test drive clinics with premium SUV buyers to determine whether customers would notice a difference between the driving feel of diesel versus gasoline models.

Land Rover engineers embarked on US testing schedule to ensure the new diesel engine could handle all US climate and terrain conditions. By the time US sales will have begun, the test fleet will have completed one million test miles, stated Land Rover.