BMW Alpina B4 vs Audi RS5

What's the difference?

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.

Good looking, good to drive, and good to simply sit in, the Audi RS5 range ticks plenty of premium boxes. Whether you can live with the practicality pitfalls of the Coupe is up to you, but if you can't, might I suggest taking a wander over to our RS4 Avant review?

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.

I defy anyone to describe the RS5, and especially the Coupe, as anything but stunning. Seriously, the near perfect proportions and swept-back styling make it look fast even when it's parked. 

Up front, there's a new-look black-mesh grille that's been given a 3D effect, like it juts out over the road in front it, while the thing headlights have been carved back into the body work like they're been windswept under hard acceleration.

The 20-inch darkened alloys fill the arches, too, with a sharp body crease that runs from the front headlight all the way back to the bulging shoulder lines above the rear tyres accentuating the curves.

Inside, the RS5 is a sea of black Nappa leather and sporty touches, and we particularly like the chunky, flat-bottomed steering wheel, which both looks - and feels - great.

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.

We only tested the Coupe, and I can tell you that the practicality perks on offer largely depend on where you're sitting.

Up front, you're spoiled for room in the two-door Coupe, with the two spacious seats separated by a sizeable centre console that's also home to two cupholders and a variety of cubbies, with extra bottle storage in each of the front doors. 

The back seat, though, is a little, or a lot, tighter, with come acrobatics required to even climb into it, given the Coupe only has two doors. The Sportback offers two more doors, which will surely make the process a little easier. 

The Coupe measures 4723mm in length, 1866mm in width and 1372mm in height, and will deliver a decent 410 litres in luggage space in the boot. The Sportback measures in at 4783mm, 1866mm and 1399mm, and boosts your luggage space to 465 litres.

Either vehicle has your tech needs sorted, with an abundance of USB and power outlets serving both front and backseat riders.

It's available as a Coupe or a Sportback, but either way, the RS5 commands a $150,900 asking price. And that's not chump change, but Audi's performance model does come with a lot of bang for those bucks.

We'll get to the engine and safety stuff in a moment, but in terms of fruit, you'll find 20-inch alloys outside, as well sportier RS body styling, sport brakes, Matrix LED headlights, keyless entry and push-button start and heated mirrors, a sunroof and privacy glass. Inside, there's Nappa leather seats (heated in the front), illuminated door sills, stainless steel pedals and ambient interior lighting.

The tech stuff is handled by a new 10.1-inch central touchscreen that gets both Apple CarPlay and Android Auto, as well as Audi's Virtual Cockpit, which replaces the dials in the driver's binnacle with a digital screen. There's also wireless phone charging, and a killer 19-speaker Bang and Olufsen sound system.

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.

Its a terrific engine, this - a twin-turbo 2.9-litre six-cylinder TFSI that will deliver 331kW at 5700rpm and 600Nm at 1900rpm, sending it thundering to all four wheels (because quattro) via an eight-speed tiptronic automatic.

That's enough, says Audi, to deliver a 0-100km/h sprint time of 3.9 seconds in the Coupe and the Sportback. Which is very, very quick.

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 RS5 Coupe will sip a claimed 9.4L/100km on the combined cycle, and emit a claimed 208g/km of Co2. It's fitted with a 58-litre fuel tank. 

The RS5 Coupe will the same 9.4L/100km, but emit 209g/km of Co2.

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.

With our time behind the wheel limited to the RS5 Coupe, we can only really report on how the two-door feels on the road, but given the prodigious power on offer, it's unlikely the addition of two doors is going to make the Sportback any slower. 

In short, the RS5 is thunderously fast, collecting speed with utter nonchalance thanks to this thick and endless-feeling supply of power unleashed whenever you plant your right foot.

It makes even the most ham-fisted attempts at cornering feel fast as lightning, with the power flow able to make up for every slow entry and exit by simply piling on pace between bends. 

But that's what you expect from an RS model, right? So perhaps more impressive is the RS5's ability to transform back into a relatively sedate urban cruiser when the red mist subsides. The suspension is firm, especially over rough road surfaces, and you do need to be a little careful with the accelerator to avoid that lurching feeling at every green light, but driven calmly, it doubles as a everyday car quite nicely.

Like in the RS4, we did find the gearbox felt a little quick to change at pace, shifting up or down at strange moments on the way into or out of corners, but you can reclaim control via the paddle shifters.

The safety story begins with six (Coupe) or eight (Sportback), and the usual suite of braking and traction aids, but then climbs into the tech-savvy stuff from there.

You get a 360-degree camera, adaptive cruise with stop and go, active lane assist, front and rear parking sensors, AEB with pedestrian detection, rear cross-traffic alert, an exit warning system, blind-spot monitoring and turn assist, which monitors oncoming traffic when making a turn.

It's a lot of gear, and it all contributes to Audi's five-star ANCAP safety rating, awarded in 2017 to the A5 range.

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.

Audi vehicles are covered by a three-year, unlimited-kilometre warranty, which is feeling more than a little underdone when compared to some competitors.

Services are due every 12 months or 15,000kms, and Audi allows you to pre-pay your service costs for the first five years, at a cost of $3,050.