The range began with the 645Ci, a modern interpretation of the traditional ‘grand tourer’, which uses a 333bhp 4.4-litre V8 and comes with a muscle-car soundtrack and performance that matches its strident styling.
But BMW is hoping to take advantage of growth in the large coupe and convertible market by broadening the 6-series offering.
Nearly 3,000 645Ci coupes and convertibles have been sold since it arrived in the UK last March, with the driver profile being mainly made up of ‘independent and affluent businessmen aged 40-55’.
However, a new six-cylinder car, offering lower running costs through its reduced price and more economical engine is expected to appeal to a younger and more mixed audience.
Now it’s the turn of the 630i (not Ci, you’ll note – something to do with overloading boot lids with letters for models specific to North America which have extra designations, so the 645Ci will go the same way eventually). It uses a new magnesium-aluminium engine, which is the lightest six-cylinder engine currently available, yet offers 258bhp.
It’s the first of a new generation of six-cylinder engines from BMW, but with 75bhp less than the 645Ci it is not unreasonable to wonder whether it was up to the job. There is no longer a deep, goose-pimple-inducing burble from the exhaust, but the 630i’s different character also has much appeal.
Offering 17bhp more than the 3.0-litre Valvetronic engine offered in the 3-series, 5-series and 7-series, maximum power is developed at 6,600rpm.
Its maximum torque figure of 221lb-ft might not look quite so impressive, but rather than a torque peak, there is a plateau reached from 2,500-4,000rpm.
It means you can bury the accelerator pedal in search of the red line, but the 630i will have gained pace well before the needle is half way round the rev counter.
And while the 3.0-litre does not have the same type of noise as the V8, it has two sides to its character. Near silent when running unstressed, it howls like a highly tuned racecar when pushed hard.
The lightweight engine also makes a noticeable difference when driving along challenging roads. The 630i feels quicker to react to direction changes than its larger engined brother, and point to point would not be much slower than the 645Ci.
Its simply a matter of being able to carry more speed into corners with the 630i, while the V8 would need to scrub off more speed, but offer an extra dose of acceleration out of the corner.
It’s as if the 630i, while clearly related to the 645Ci, feels a little more lively and athletic, although it might not have the same outright grunt.
The engine has reasonable fuel consumption for what is still a large, heavy coupe, achieving about 30mpg on the combined cycle.
However, a few weeks ago Fleet News reported that BMW is evaluating the case for slotting a diesel engine in the 6-series, which might result in a 635d during 2006. A 6-series that combines 272bhp, 413lb-ft, about 220 g/km and 34mpg really would be an alluring prospect for a company director.
Model: BMW 630i
Engine (cc): 2,996
Max power (bhp/rpm): 258/6,600
Max torque (lb-ft/rpm): 221/2,500
Max speed (mph): 155
0-62mph (sec man/auto): 6.5/6.7
Fuel consumption (mpg man/auto): 31.4/29.7
CO2 emissions (g/km man/auto): 216/226
Fuel tank capacity (l/gal): 70/15.4
Transmission: 6-sp man/6-sp auto
On sale: Now
Price (OTR): £45,255-£50,655