A COMPELLING blend of supercar performance and executive refinement has been put together by BMW to create a new flagship for its 5 Series range.

The M550i sits at the top of 5 Series line up and in every way is almost as potent as the mighty M5 high performance saloon.

It's powered by a 4.4-litre V8 engine developing 530 horsepower and that results in blistering performance of 0 to 60 in just 3.8 seconds with its maximum speed restricted to 155mph.

Fuel economy for such clout is officially rated at up to 25.9mpg with emissions of 247g/km yet on our drive in the M550i we bettered that and saw an average of 26.2 to the gallon.

The soundtrack from the V8 is an absolute delight as the car goes through its paces and it handles with impeccable manners.

Performance is enhanced by an M Sport differential and adaptive suspension as well as BMW's xDrive all-wheel-drive system which gives the M550 a superlative poise.

The M550 xDrive M Sport saloon costs from £71,365 making it some £20,000 cheaper than the M5 and only the most diehard of performance drivers would spot any real difference.

After all, what's 0.4 of a second in 0 to 60 acceleration time?

The M550i also packs a degree of class that sets it apart. It sits on 20-inch alloys, has splendid grey detailing outside while inside it is sumptuously appointed.

Quilted leather upholstery, seatbelts detailed with subtle M Sport stripes and BMW's latest connectivity systems with a 12.3-inch display screen are part and parcel of a luxurious, high tech approach.

The car cossets like few can and makes driving a pleasure - no matter what you demand.

Three drive modes - comfort, sport and eco - are available and the car reacts instantly to whatever you choose.

Sport gives real bite to its characteristics, eco softens everything down while comfort mode is ideal for everyday needs.

The eight-speed automatic transmission can be operated manually via steering wheel mounted paddle shifters and as such changes are rapid and precise.

It's hard to fault the M550's manners under any circumstances and at all times the driver feels a massive degree of intimacy with the car. It does exactly what is asked.

A head-up display and a crystal clear layout to the instrumentation are other attributes while an auto hold function for the parking brake makes driving so easy, especially in traffic.

For added convenience the latest 5 Series models come with ‘over that air' updates for the software systems - an automatic set up similar to that of a smartphone update and the car is now fully compatible with either Apple or Android devices.

Exterior styling is quite conservative and the only real clue to the awesome might of what lurks beneath the M550 are possibly the red brake callipers within the wheels.

In every way the M550i is a masterpiece of all things BMW - astonishing performance, incredible engineering and packaged in absolute luxury.

The core 5 Series range now starts from £39,270 for the 520i and the M550i tops the eight model saloon range in splendid fashion.