Audi is gearing up for its next new car family. This year may bring the TT MkII and Q7 SUV, but 2007 heralds the new A4 range, ultimately comprising five bodystyles (and two model series).

The new mid-ranger gets an all-new platform, which insiders claim marks Ingolstadt’s biggest development since the A8 switched to aluminium construction. Audi has high-performance engines nailed, and limpet-like grip levels from quattro models; now it is overhauling its chassis design to improve steering feel and weight distribution.

The engine and gearbox have been shunted back in the chassis to make the next generation turn in more sharply. Front-to-rear weight distribution drops from 62:38 to 59:41, a little closer to BMW’s much-vaunted 50:50.

And following the example set by the new RS4, another ratio is tweaked. Torque will be split 40:60 in favour of the rear tyres on all quattro models, which should help sharpen handling. The benefits aren’t merely dynamic: relocating the engine will also enable designers to cut the front overhang, making for sportier proportions.

Further changes to the hardware include a new steering rack and overhauled suspension design, which should make an Audi’s ride more forgiving on Britain’s crumbling roads.

The first car to showcase the new platform, codenamed B8, will be next year’s A5 coupé. This is the production version of 2003’s Nuvolari concept. The next four-seat cabriolet, due in 2009, should also wear the A5 badge.

The A4 saloon arrives in late ’07, followed by the Avant around eight months later. The other all-new variant comes at the end of 2008, when the Roadjet concept makes production.

The B8 chassis wasn’t the Roadjet’s only sneak preview. The front end, with its more aggressive vents, slanted headlamps and ubiquitous single frame grille, betrays the A4/A5 face. The flanks get more pronounced sculpting and crisper lines.

And, of course, the new bodystyle is a given. Although Audi doesn’t like the comparison, the Roadjet resembles Vauxhall’s spacious hatchback, the Signum. The Audi has a higher roofline – 130mm taller than today’s A4’s – for higher mounted seats that make for heaps of legroom. The driving position is more commanding, too.

Don’t think of the crossover Roadjet as Audi’s answer to the BMW X3, however. A conventional five-seat SUV – the Q5 – follows in 2009, as Audi continues its growth drive.