Their counterparts at Audi seem to be doing a better job, as proved with the new A8 Hybrid that combines a 2.0-liter four-cylinder petrol with an electric motor for a fuel economy of 6.4 liters per 100 km (36.8mpg US).
This brings us to the new ActiveHybrid 5 sedan that was introduced today, ahead of its sales launch in March 2012.
The new 5er, which is identified by the "ActiveHybrid" badges and the bespoke alloy wheels, combines BMW's 300HP 3.0-liter TwinPower Turbo inline six-cylinder with an electric drive system and an eight-speed automatic transmission. The electric motor delivers an output 55-horses and makes 155 lb-ft of torque available from rest.
BMW says the system generates a combined output of 335-horses and up to 330 lb-ft, allowing the sedan to accelerate from 0 to 60 mph (96km/h) in 5.7 seconds (preliminary). That's the same time needed by the standard 535i sedan with 300HP, which returns 30mpg highway and has an MRSP of $52,250.
BMW has not yet revealed pricing nor fuel economy figures for the hybrid version of the new 5-Series.
What the company did say about the ActiveHybrid 5 is that the lithium-ion battery can store enough energy to give the car an all-electric driving range of up to approximately 2.5 miles (4 km) at an average speed of 22 mph (35 km/h). BMW added that the sedan also features ECO PRO mode, which switches off the combustion engine while coasting at speeds of up to 100 mph (160 km/h) to further improve fuel economy.
More details are to be released at a later date. As for the question we posed in the title, obviously it will all depend on if it will offer any significant gains in fuel economy and at what price compared to the standard 535i.