SIX is the operative number for BMW’s E63/4 6 Series as prices rise by more than $6000 and fuel consumption falls by about six per cent on the eve of its sixth year on sale in Australia.

Out now from $227,300 for the Coupe (up by $6139) and $245,100 for the Convertible (a $6144 increase), the 5 Series-based two-door sports/luxury grand tourer boasts blink-and-you’ll-miss-it styling changes, improved mechanical efficiencies and an upgrade in cabin functionality.

However, while the outputs of the 4.8-litre Valvetronic V8 petrol powerplant are unchanged, the bonnet above scores “arrow-shaped character lines” in an effort to bring some visual differentiation to the BMW sports cars. Also new are a revised exhaust system with dark chrome rear outlets, BMW Individual high-gloss shadow line and 19-inch alloy wheels (up one inch) with 245/40-section front and 275/35 rear tyres.

But the biggest news is the adoption of BMW’s Brake Energy Regeneration system from BMW’s EfficientDynamics technology catalogue.

This cuts combined-cycle fuel consumption by more than five per cent on both the Coupe and Convertible.

By generating electric power from energy otherwise wasted as lost heat via the brake system, the Coupe’s petrol economy improves by 5.4 per cent, from 11.1 to 10.5 litres per 100km, while the Convertible’s drops by 6.8 per cent, from 11.7 to 10.9L/100km.

There are no changes to the 650i’s 270kW/490Nm 4799cc 4.8-litre Valvetronic petrol V8 Sprint times to 100km/h are covered in just 5.2 seconds in the Coupe, and 0.4s more for the droptop.

Cabin titivations include the fitment of BMW’s latest iDrive control system from the F01 7 Series range, which introduces a high-resolution monitor with navigation, high-definition television and 80GB hard drive.

Similarly, the 6 Series’ brushed aluminium interior highlights can be changed at no extra cost to Birch Grain or Maple Grain woodgrain trim, while standard features continue to extend to a BMW M steering wheel, anthracite-coloured BMW Individual roof lining and a lighting package.

Two new exterior colours arrive – Imola Red and Carbon Black – while the interior on both models continues to come as standard in Pearl leather, with the no-cost option of Saddle Brown light, Chateau, Cream Beige or Black.

The last 6 Series change occurred when the Series II facelift was introduced in early 2008, gaining a mildly massaged front and rear, BMW’s latest drivetrain, and a name change from 650Ci to just plain 650i.

November 2009 marks five and a half years since the E63 6 Series range was introduced to Australia.

In that time around 880 customers have responded to the controversially styled grand tourers’ mix of luxury and sports car performance, with numbers averaging out to about 165 per year. 2006 was the 6 Series’ most popular, with 228 sales.

The E31/E38 8 Series from 1989 to 1999 preceded the E63/4 6 Series in BMW’s rich history of coupes, but high prices and a worldwide recession at the time saw the technologically advanced 2+2 seater struggle to scrape 31,000 sales over its ten-year run.

It also lived in the shadow of the ‘classic’ 6 Series available from 1976 to 1989 and immortalised as Cybill Shepherd’s company car in the hit 1980s TV comedy Moonlighting. Some 86,000 were made over the 13-year run.

Earlier BMW coupes include the 327 of 1938, the V8-powered 1956 503 and the 2000 CS of 1965, which morphed into the 2800 CS and shark-like 3.0 CSi of the 1970s.