Audi RS4 vs BMW Alpina B4

What's the difference?

What a way to send off this generation of Audi RS4 and RS5. The extra focus courtesy of those trick coil overs and drama from the exhaust plus the sharper gear changes deliver the best Audi has done with these RS products. 

There are some compromises, with the suspension favouring outright control over low-speed comfort. It’s also true that the current BMW’s M3 and M4 are more impressive, but when the products are nearly seven years fresher than Audi’s, what do you expect? 

Plus, those looking for a more restrained and polite fast executive sedan (or wagon) will gel with the Audi’s sophistication. There aren’t many of these Competition Plus RS4 and RS5s coming to Australia and they are impressive visually and from behind the wheel. It’s a fitting way to send off the current generations.

Note: CarsGuide attended this event as a guest of the manufacturer, with accommodation and meals provided.

You could almost call the B4 S the anti-M4. It's still fast and practical but from a completely different perspective. It's much more a grand tourer than the M4 and even with the Akrapovic exhaust (usually a byword for joyous, anti-social racket), subtle.

For some, the price won't matter because the Alpina delivers what they want - M4-like straight line performance without the histrionics or the uncompromising chassis. And there's also a bit of that perverse exclusivity of the styling that you won't get anywhere else.

The RS4 Avant’s 'Progressive Red' metallic helps the black milled 20-inch alloy wheels pop. Its stance is hugely purposeful with wheels tucked right up in the blistered arches courtesy of the lowered ride height — it's how the Avant would have looked in a design sketch.

The visual bulk of the long-roofed RS4 gives it the sort of proportions motoring journalists love to wax lyrical about, even if plenty of buyers still prefer coupes or lifted SUVs. 

The RS5's more flowing, elegant lines match well with the Navarra Blue paint work, silver-accented wheels and conventional leather-appointed seats within. 

Both cars have effectively identical front cabins reflecting Audi’s classy and sleek design language. The integration of technology is pretty good and the RS4’s additional red styling pack really makes it feel sporty within.

Alpina has always had a particular aesthetic that could uncharitably be termed as mid-'80s West German - all set square angles and body graphics. Think David Hasselhoff's Berlin Wall look. The company has never really deviated from adding squared-off body bits to the various BMWs it has rebadged under its long-running agreement.

For the B4S, Alpina adds the signature billion-spoke alloy wheels (only a slight exaggeration), a new front splitter complete with Alpina lettering, a weirdly proportioned boot lid lip spoiler and - not even joking - pinstripes. Like I said, mid-'80s West German. You can still recognise the sleek 4 Series Coupe but perhaps the worst of it is the super-sized, wonky-looking ALPINA B4S on the boot.

Inside is rather more restrained apart from the ill-fitting Alpina plaque under the climate control. Again, it's all 4 Series in here, with the lovely Merino leather liberally applied across the cabin. Less lovely is the wood on the door pulls and console but the door cards have an oddly appealing woven leather which looks and feels good.

Sadly the standard 4 Series steering wheel is along for the ride. There's nothing wrong with it - although the Alpina logo does look out of place - but if I were a product planner, I'd beg for the lovelier M wheel.

The RS4's cabin is excellent, with a good mix of physical buttons and responsive touchscreens for control. There’s enough storage space for this kind of vehicle, with good door bins and well-sized cupholders in the centre as well as USB-C and -A charge points. 

Audi’s multimedia system is friendly though the large touch targets and dark background aren’t as crisp as those fitted to the latest rivals. The screen isn't as big, either, measuring 10.1 inches for the multimedia item. The RS4 supports wireless Apple CarPlay and Android Auto.

That said, Audi’s 12.3-inch digital driver’s display with bright and poppy mapping software and generous customisation remains right at the head of the pack. 

There is a panel of switches below the touchscreen for climate control, physical selection of the five-or-so drive modes and a collection of helpful buttons on the perfectly-shaped and sized leather-appointed steering wheel.

It lacks F1 or DTM wow-factor compared to the C63 and M3 with their easy-access driver mode buttons and toggles on the steering wheel but the RS4's restrained looks will resonate with those that prefer a bit more elegance inside. 

Neither the RS4 nor RS5's back seats are designed for those over about 175cm. The RS4’s roof is a little higher so it is good enough for most adults but the RS5’s sloping profile compromises things. It has two individual buckets compared to the RS4’s three-wide bench. 

Rear seat passengers get air vents, an individual climate zone, bottle holders in the doors, USB charge points and ISOFIX attachments for the outboard seats, with matching top tethers in the seat backs.

The Audi RS4’s boot is a generous 505L with under floor storage and a netted area on the driver’s side. Folding the 40/20/40 split-fold bench increases space to 1495L. That said, the RS5’s 465L is still very good, though it is not quite as practical in the real world. 

Being fitted with roof rails makes for sleek integration of roof racks for the RS4 to slip roof pods, bike racks or whatever else you might choose to take on a trip away.

If you're in the front, you're in luck - it's a comfortable place to be, with plenty of leg and headroom. Down back isn't terrible despite the coupe roofline. The two seats are nicely shaped for maximum comfort and separated by an odd plastic tray. The fold-down armrest has two cupholders.

Front seat passengers score a pair of cupholders (bring the total to four for the car) and the long doors will hold a bottle each.

The boot swallows a reasonable 445 litres, which isn't at all bad.

If you thought BMW don't mess about when pricing up its cars, you best strap yourself in. The 440i-based B4S starts at a solid $149,900. That's $48,000 more than the 440i and significantly more than an M4 Pure. But there's plenty of gear on offer and some genuine, bespoke Alpina additions.

Standard are 20-inch signature Alpina alloys, 16-speaker harmon kardon-branded stereo with DAB, super-soft Merino leather everywhere, dual-zone climate control, around-view cameras, reversing camera, sat nav, keyless entry and start, front and rear parking sensors, active cruise control, heated and electric front seats, head-up display, auto headlights and active LED headlights, LED taillights and electric sunroof.

The stereo and sat nav are run by BMW's iDrive. It's a cracker of a system and almost gets away without Apple CarPlay and Android Auto. The absence of such simple pleasures at this price point is a bit lame, but here we are.

Audi’s 2.9-litre twin-turbo petrol V6 has seen plenty of use across performance products from Audi and Porsche, including the Macan S and Audi S6. 

In the RS4 and RS5 Competition Plus, it develops the same 331kW (at 5700-6700rpm) and 600Nm (at 1900-5000rpm) as the regular car. This makes it an extremely flexible engine that delivers predictable punch anywhere in the power band.

That said, it lacks the explosive character of BMW’s twin-turbo inline six — the figures are only 15kW and 50Nm higher on paper yet the M3’s response is that much more ferocious. 

Audi’s RS division has tried to capture a bit more emotion, retuning the eight-speed torque converter automatic transmission for crisper shifts. This also benefits the RS4’s 0-100km/h sprint time, which falls two tenths to 3.9 seconds in Competition Plus guise. 

The V6 breathes a little easier, too, with a different exhaust. Audi says the extra sound is down to 8.0kg less sound deadening in the car.

There’s more resonance at idle that does feel tiring sitting in traffic idling but the trade-off is a brawny mid-range baritone that develops into a shrill bark approaching the redline.

A lot of your extra money turns up under the bonnet. These days the 440i packs BMW's slick B58 turbo straight six and the B4S does likewise. The boys from Buchloe in Bavaria (there are certain to be women there, too, I just liked the alliteration) added a pair of Alpina-spec turbos to generate a whopping 324kW and, more importantly, 660Nm. Alpina says 600Nm (the max torque figure of the brilliant M4 CS) is available from 2000-5000rpm, while the full 660Nm is available from 3000 to 4500rpm.

The M4 Pure has 317kW and 550Nm from the S55 straight-six. Just so you know.

Like the 440i but unlike the M4, the B4S employs the dependably brilliant eight-speed ZF automatic found throughout the BMW range.

The Audi RS4 wagon is rated to use 9.5L/100km in ADR combined cycle (urban/extra-urban) consumption testing while the slipperier RS5 returns 9.4L/100km in the same test. 

We weren’t able to run accurate or particularly relevant fuel figures on the event but the trip computers showed around 12L/100km in both RS4 and RS5. 

While these numbers are high compared to your average passenger car, the Audi is more efficient than BMW's rivals, and gets remarkably close to the hybrid C63 in the real world.

The fuel tank is quite small for this kind of vehicle at 58 litres. That limits the RS4’s theoretical driving range to 611km. 

Unsurprisingly, the Audi RS4 and RS5 require 98 RON premium unleaded petrol. 

Alpina quotes 7.9L/100km on the combined cycle and we went through the premium unleaded at the rate of 11.7L/100km. I enjoyed myself, so that's not a terrible result.

The time allocated to driving the RS4 Avant Competition Plus was fairly limited and we were sadly unable to sample how the highly adjustable coil over suspension performed where it makes most sense — on the racetrack. 

Still, winding country roads between Sydney and the Southern Highlands served up some challenges, demonstrating how the Competition Plus pack changes the character of the RS4 and RS5. 

The only real negative is comfort, specifically over those horrible plastic speed bumps that litter shopping centre car parks. With adaptive dampers, carmakers can set programs for these kinds of obstacles to soften and stiffen the clever shocks at just the right time. Not so the Competition Plus pack cars, which ride these bumps harshly.

That about does it, though, and everything thing else is a net benefit. The steering system addresses some criticism of the earlier RS4s. Further than a retune, the Competition Plus gets a new rack, that is non-progressive with a fixed ratio of 15:1 (instead of 13.3:1) and 2.4 turns lock-to-lock. The reactions to each input feel a hint more faithful. 

When above 40km/h the coil overs come into their own. Even though the RS4 rides firmly it doesn’t constantly jiggle over small bumps. Over sharp-edged hits, the suspension rounds the hits off so, while you feel them, there’s a sense of control and sophistication. 

Having speed limits to contend with means it is essentially impossible to find the limits of grip of the 275/30R20 Continental SportContact 6 tyres on the road and there isn’t much body roll, either.

The RS4 is still rewarding, though, getting up on its toes just enough through a series of bends to feel engaging. It gives an impression of being quite light and at 1820kg it is now considered featherweight next to rivals.

The RS4's Quattro all-wheel drive system favours the rear wheels when driving normally (60 per cent rear) and can send up to 85 per cent of the drive to the back axle. 

The tweaked electronically-controlled rear limited-slip differential amplifies the throttle steer-ability of the RS4, giving you the confidence to squeeze the gas on exit. 

It helps that the Competition Plus bucket seats are a little thinner and set closer to the floor giving you more feedback. This is the key differentiator between the RS4 and RS5 we drove — the buckets make the car feel alive. 

Strong brakes are made up of 375mm front rotors clamped by six-piston calipers. Optional carbon ceramic brakes with larger 400mm front rotors help save 6.5kg and, if you plan to use the RS4 on track, are a smart buy along with a set of Pirelli P Zero Corsa semi slick tyres ($850). 

Really, though, neither the RS4 nor RS5 are the perfect car for the track. They are plenty capable and fast on the road with just enough fun, reward and character thrown in to keep you coming back for more.

One of the key differences between the B4 and M4 is the ride. While the M4 can crash over bumps and generally be a little hard to live with, the crew in Buchloe have gone after a much more plush ride. And in that they have succeeded because the B4 S is a mighty fine cruiser. Bumps are dismissed with a haughty disdain, even Sport + silliness doesn't completely write-off ride quality.

Very impressive too, is the steering. While still not at Lotus Elise levels of feel (few cars are), the Alpina tweaks connect the your palms to the road with more clarity than what you'll find in the 440i or M4. Where the M4 particularly adds too much weight, the 440i is a bit more circumspect in that regard.

And then we come to the engine. The B58 six is a belter, better even than the N55 that preceded it. It's still a 3.0-litre straight six but is part of BMW's modular engine family that starts with a 1.5-litre triple in the Mini and 1 Series. The Alpina-spec turbos are noisier, the Akrapovic exhaust lighter and also noisier. It doesn't have the all-out crackle and pop of an Audi or Merc (perish the thought), but when you're on it, the B4 means business. The 660Nm of torque, available over a wide rev range, delivers a steel fist wrapped in a velvet glove and bubble wrap - the speed builds rapidly but smoothly. 

The approach to the chassis tune seems to be based on the driving talents of mere mortals on normal roads, which is kind of like the 440i. It's terrific fun to drive hard but it's very forgiving and patient. The great thing about it is that you wouldn't think twice about jumping in it for the long haul, so comfortable and quiet is the cabin. The M4 will leave it for dead on a winding road, but that's perfectly fine.

One irritant is the replacement of the admittedly cheap BMW gearshift paddles with weirdly non-tactile buttons. They're not particularly easy to use and, probably worse for a sporty car, unsatisfying. It's an odd detail with which to go off the reservation. Cheeringly, the eight-speed ZF is its usual perfect self, so you don't have to worry too much about manual mode or go old school and use the shifter.

The Alpina ships with six airbags, ABS, stability and traction controls, ABS, stability and traction controls, forward collision warning, forward AEB, road sign recognition and active cruise control.

There are also two ISOFIX points in the rear. Neither the Alpina nor the 4 Series has an ANCAP safety rating.

Audi covers the RS4 and RS5 with a five-year/unlimited kilometre warranty which is now the expected norm across the premium part of the market. 

A five-year service plan can be pre-purchased, costing $3630 for both models with maintenance due annually or every 15,000km. 

After the five-year warranty period, owners can choose to extend the service packaging and warranty for two extra years at a cost of $4260. This can be done twice, extending the warranty up to nine years.

Alpina offers a two-year/unlimited-kilometre warranty which is a bit behind the times and not in keeping with the price point. Servicing is another matter altogether and you're subject to your dealer's standard charges for servicing.