After a leak earlier in the week, which we carried here, Mercedes-Benz has decided to reveal everything about their all new B-Class ahead of its world debut at Frankfurt next month. To sum it up, Stuttgart says that their new ‘Compact Sports Tourer’ is ‘substantially more agile and efficient, but as comfortable and spacious as ever’.

As expected, the new B-Class has a substantially bigger footprint that the car it replaces. At 4,359 mm long and 1,786 mm wide, it’s 89 mm longer and 9 mm wider, although the new car sits 46 mm lower than before. Accordingly, the seat height in relation to the road has also been reduced by 86 mm, for easier vehicle entry, says Merc. They add that in response to customer requests, the sitting position is now more upright.

For those at the back, which is important for this model, a lowering of the vehicle’s floor at the rear produces segment-leading rear legroom (976 mm) that even surpasses that of the E and S-Class! And despite the lower roofline, headroom has been further improved over the old car.

Additionally, there’s an Easy-Vario-Plus system that includes fore/aft adjustment of the rear seats by up to 140 mm (increasing boot volume from 488 to 666 litres) and a front passenger seat which backrest can be folded forward onto the seat cushion.

Now, the B’s new looks might not be agreeable to all, it’s hard to argue with its slippery drag coefficient of 0.26. This is helped by areas such as air flow around the front wheels, underbody design and the cooling air flow. Patents are pending for details such as the serrated wheel arch spoiler. An upcoming optional Eco Technology package will bring the Cd figure down to 0.24, which is on par with the E-Class Coupé and impressive for a hatchback shape.

The new M270 engines feature Merc’s third-generation direct injection system that first surfaced in last year’s BlueDirect V6 and V8 engines. Both are 1.6-litre turbocharged units with max torque available from 1,250 rpm. The one in the B 180 is rated at 122 hp and 200 Nm, while the B 200 has 156 hp and 250 Nm.

The diesels are based on the OM651 family used from the C to the S-Class, but with displacement scaled down to 1.8 litres and mounted transversely for the first time. The B 180 CDI generates 109 hp and 250 Nm from 1,400 rpm, while the B 200 CDI packs in 136 hp and 300 Nm from 1,600 rpm. All engines can be paired to a new 7G-DCT dual clutch transmission or a new six-speed manual, which Merc says is closely related to the DCT.

Mercedes promises improved agility, thanks to the new B’s lowered centre of gravity, a new four-link rear axle and the upgraded ESP. A sports suspension is optionally available. This one further lowers the ride height by 20 mm and features sports dampers with amplitude-selective damping and Direct-Steer (faster, sharper response) for the electromechanical steering.

The new B is build with a modular ‘Energy Space’ concept that’s designed to accommodate versions with an alternative drive. There are interfaces in the body shell that enables the floor panel to be easily modified, plus an underfloor compartment covering part of the area under the rear bench seat for ‘alternative energy accumulators’. So it looks like we can expect some sort of hybrid B-Class in the future, too.

Full gallery after the jump.