Twenty-one years after Alfa Romeo introduced its first 4x4 road car, it is rolling out another generation of all-wheel-drive technology this autumn. (The other four generations, if you're interested, were the 1983 33, the 1991 33 Permanent 4, the 1992 155 Q4 and the 1994 164 Q4. All these 4x4 systems were different.)
But this time it's not another ultra-low volume flash in the pan. Because under the skin of the two 156 Q4 models - both estates, one called the Crosswagon with raised suspension and aspirations to be an Audi All-Road, the other slightly lower and using the existing Sportwagon tag - is Alfa's new-generation permanent four-wheel-drive system, dubbed Q4. The importance of Q4 is that it will underpin virtually all of the company's new-generation models, including the 156 replacement, the 157.
The Q4 system is unique in that although it's hooked up to a transversely mounted engine, it's a permanently engaged four-wheel drive system in the mould of Audi's quattro running gear.
Rival systems - such as Volvo's AWD or the VW Group's 4motion - run as conventional front-wheel drive systems until the front wheels begin to slip. Then a Haldex clutch is electronically activated, sending torque briefly to the rear wheels. But when the slipping stops, so does the all-wheel drive.
Paulo Massai - Alfa's VP of Engineering - was dismissive of rival Haldex-based systems and vocal about the superiority of Alfa's new three-differential design.
Massai told evo that the Q4 system benefits from instant torque transfer and doesn't need to detect a skid. In a steady state, Q4 sends 58 per cent of the engine's torque to the rear wheels, which should result in a much more 'rear-drive' feel than any other transverse-engined car can manage.
The key is the new Torsen C central differential. When accelerating hard, the C diff can shift as much as 70 per cent of the torque to the rear wheels. However, if the car is oversteering, the Q4 shifts 60 per cent of the torque to the front wheels, partly to give the rears a chance to regain grip. On slippy surfaces, individual wheels can be braked and the torque shifted to the opposite wheel, which should have more grip.
So much for the theory. Time to test the reality in the Crosswagon and Sportwagon Q4s, both powered by the same 150bhp JTD turbodiesel, and neither of them for sale in the UK. Still, on the snaking roads of Sardinia they will at least give us a flavour of what the forthcoming 157 could be like.
If you're a fan of this kind of thing (and I am) the Crosswagon looks fantastic. The interior is stunning too, especially the wooden-rimmed steering wheel and steel dash trim. Engine refinement is OK for a modern turbodiesel, but is pretty intrusive at high revs. Thanks to the punchy 225lb ft at just 2000rpm there's good, though hardly tyre-burning, overtaking performance.
The very aggressive, washboard off-road section of the launch route showed up the 156's lack of body stiffness, with the rear view mirror vibrating and the tailgate chattering in sympathy with the ridges. In real-world use, though, an appealing vehicle.
The Sportwagon is more of a driver's car, though it, too, rides on slightly raised suspension. It felt peppy, though a single-turbo diesel engine is not at its best on demanding switchbacks, where it's easy to 'fall off' the torque curve.
The SW feels very surefooted on the really twisty stuff and is happy to be pushed hard on the more open mountain roads, the Q4 transmission helping it stay resolutely neutral, with virtually no tyre scrub or washout from the front end. It clearly follows your intended path through the distribution of torque rather than just relying on the grip of the tires.
And it's surprising that as the SW exits a hard-driven switchback, there's little lurching weight transfer in the opposite direction. This car stays together no matter how often or tight the changes of direction. When the front tires do eventually give up the ghost, they slide gently. On fast, sweeping roads, the SW was swift and flowing. Impressive.
The SW's main problem is the steering. It not only suffers a lack of bite but the car doesn't respond quickly enough to the first quarter-turn of lock. The way to adjust to this perceptible time-lag is to turn-in a fraction early.
The SW feels like a car of two distinct parts: razor-sharp running gear and an aging platform and steering. But I discovered enough to know that when the 157 is launched, the Q4 system has the potential to make it into a serious driver's car.
