So to bring together a couple of fast estates is not only a welcome break from the seemingly endless diversification of ranges, it's a reminder of just how good the formula is. It won't spoil the test to say that both cars here are very good, more than fast enough for most and boasting good practicality too. There are no tricks, no gimmicks, no pretence of being something that these cars aren't; they are two mid-size estates, each with 3.0-litres, six cylinders and around 350hp, tasked with being fast, fun and stylish where required. Which is the best?
Even with Alpina's enviable reputation, the D3 doesn't enter this contest looking all that competitive. It's the more expensive car here despite being the older design - a point we'll come back to - it lacks any particularly fancy way to transmit its power to the road (the Quattro Audi also has a rear Sport Differential) and, well, it is a diesel. Good though the latest diesel engines are, the D3 does seem to be entering this with one hand tied behind its back.
Moreover, the more languid gait of an Alpina set up against M cars suits the D3 well. In a B3 saloon comparisons are inevitably made to the M3, but here there is no rival. And where that final layer of sharpness could prove frustrating in a petrol saloon, is it that important where diesel estates are concerned? It feels balanced, fluid and composed for the vast majority of the time, though from previous experience the optional limited-slip diff would be a worthwhile option with 516lb ft to contain...
That the D3 does all this with the usual 3 Series refinements and a few lovely Alpina touches makes it all the more desirable. The interior may not be as fancy as the Audi's but, as a car to drive and an object to admire, it remains an excellent prospect.
You've dismissed the Audi already, haven't you? Too bland, too heavy, too inert to compete with the finely honed Alpina. Well don't be so sure...
the road test, this is a fast Audi with some real quality to its dynamics, with a well sorted ride and a Sport Differential that can be felt proactively distributing power at the back. It's probably the faster car here across the ground, powering out of corners authoritatively where the Alpina can be found falling back a tad clumsily.
Its weight advantage will help too; it isn't huge at 55kg but it means that the Audi is less than 1,800kg with a driver and the Alpina, well, isn't. This feels a better balanced 'S' product than before too, with less nose heaviness to its handling and a pleasing level of agility.
Perhaps it's unfair to make the point here given the Alpina is a diesel - don't forget the B3 is available too - but the Audi's petrol V6 feels especially good here. It picks up swiftly from very few revs, feels strong through its mid range and is more than happy to snarl its way to 7,000rpm. Even against petrol opposition you sense this 3.0-litre would fare well.
The powertrain is where the Audi's weaknesses begin to become exposed though. The automatic gearbox simply isn't as decisive as the Alpina's, with a tendency to offer gears you don't want at a time you don't need them. Of course manual control is available, which improves the situation, but then the Alpina is fine in that regard too...
If this sounds harsh, that's probably because it is. Both of these cars are talented and likeable estates, proof that there is still life in the old dog carrier yet. They can't even be separated on practicality grounds, the Audi boasting 505 or 1,510 litres of boot space against the D3's 495 and 1,500 litres. See, it's not all powerslides and tyre smoke around here...
If the latest in technology, style and equipment matters to you and your family, the S4 comes highly recommended. Typically we don't focus on those attributes of a car much on PH, but the Audi is a clear step ahead of the Alpina inside. Given how much time we all seem to spend in cars, that has to be a consideration.
On that basis though how the car drives should matter too and, while the Audi is good, the Alpina is better. Yes, even as a diesel. In areas where a regular BMW disappoints the Alpina impresses, delivering a level of quality and finesse to the way it drives that often escapes non-M products. That it does this without attracting the unwanted attention of an M car and returning 60mpg in the right circumstances only strengthens its case.
You will have noticed the Alpina is significantly more expensive here though, even without the £1,890 limited-slip differential. There are simple ways to save money on our test car though - see the £1,180 panoramic sunroof, £945 electric seats and £825 head-up display - which will begin to return the price difference to somewhere near the £5,535 gap that separates them as standard. The Alpina feels the more expensive product, entirely justifying its £50K start price and not feeling terrible value at £58,000 either. Petrol or diesel, saloon or Touring, there simply isn't a bad Alpina 3 Series - if you can get into an Alpina somehow, you'll love it.
ALPINA D3 BITURBO TOURING
Engine: 2,993cc, straight-six twin turbocharged diesel
Transmission: 8-speed automatic, rear-wheel drive
Power (hp): 350@4,000rpm
Torque (lb ft): 516@1,500rpm
Top speed: 170mph
Weight: 1,730kg (unladen)
Price: £49,950 (As tested £58,115 comprising Alpina classic 20-inch for £860, Alpina piano black with insigna for £340, electrally folding with anti-dazzle exterior mirrors for £300, Matt aluminium exterior trim for £155, £825 for Head up display, £215 for Anthracite headlining, £675 for Harman Kardon loudspeaker system, £265 for electrically adjustable lumbar support for driver and passenger, £1,500 for BMW professional media package, £1,180 for panoramic glass sunroof, £330 for reversing assist camera, £945 for seat adjustment, £220 for speed limit display, £90 steering wheel panel in black leather and £265 for sun protection glass)
AUDI S4 AVANT
Engine: 2,995cc, V6 TFSI
Transmission: 8-speed tiptronic, Quattro all-wheel drive
Power (hp): 354@5,400-6,400rpm
Torque (lb ft): 368@1,370-4,500rpm
0-62mph: 4.9 secs
Top speed: 155mph
Weight: 1,750kg (EU with 75kg driver)
MPG: 37.7 (NEDC combined)
Price: £44,415 (As tested £49,770 comprising Misano Red paint for £645, Quattro sport with Sport Differential for £1,200, 19-inch diamond cut wheels for £550, Light and Vision pack for £750, Adaptive S Sport suspension with damping control for £900, Audi phonebox with wireless charging for £325 and on the road costs of £985)