- Published in Technology.
BMW has fitted electric power steering (EPAS) to the 7 Series luxury sedan, making it the only vehicle in the segment to feature the technology.
Replacing the previous model's hydraulic system with EPAS reduces parasitic losses on the engine, improving efficiency. The 190kW 730d model now consumes 6.8-litres/100km. Emissions are 148g/km CO2 – claimed to be best-in-class for a six-cylinder diesel.
BMW said: “The system offers savings of up to 3%. No electrical power is consumed during straightline driving or steady-state cornering. Noticeable attributes of this system include not only its high efficiency and low weight, but also high steering precision with good feedback, and comfort-enhancing self-centering and anti-roll characteristics.”
While EPAS is common in smaller vehicles, hydraulic systems still dominate the luxury segment, where vehicle weight and the desired steering attributes have made the latter more suitable.
But improvements to motors and software have made EPAS applicable to other applications too, and now all BMW sedans from the 1 Series to 7 Series use electric steering, with the exception of the latter's all-wheel drive variants.
The 730d is 17% more efficient than the outgoing model: as well as the EPAS system, a more efficient engine, a lower 0.28Cd figure and an eight-speed automatic with a wider 7.07 ratio spread and 'sailing' function all contribute.