BMW is already testing a mildly reworked version of its Mercedes E-class-rivalling 5-series, a model likely to make its public debut at the Frankfurt motor show next September.

While development of the new car still has the good part of a year to run, changes being made to the 5-series appear less significant than those adopted by the new E-class.

Externally, the bumpers are more heavily structured and the lamp graphics revised, but on the evidence of the prototype caught here testing in Munich, the existing bodywork is largely untouched.

Inside, BMW plans to provide the 5-series with the latest version of its iDrive multimedia system and a configurable instrument display already recently introduced on the facelifted 7-series.

On the engine front, the twin-scroll turbocharged 3.0-litre in-line six-cylinder petrol engine in the 535i is set to gain an added 14bhp, lifting its reserves to 316bhp in the new 540i model.

The twin-turbo 4.4-litre V8 petrol engine in the 550i is also expected to get added firepower. Munich insiders have already confirmed a 43bhp increase to 444bhp.

Thanks to: Autocar