KTM X-Bow vs BMW Alpina B4

What's the difference?

Okay, so rain is not your friend. Neither is brutal sunshine, strong winds or any speed bump anywhere. There are probably a handful of times you'll want to drive it, and when you do you will definitely get hit in the face with rocks and bugs, and spend most of your time wondering just how the hell this thing is legal.

And yet, we are hopelessly, head-over-heels in love with it. It's an absolute weapon on a track, a joy on anything even resembling a twisting road and it is one of the few genuinely unique cars on the road today. And the fact it exists at all is a cause for absolute celebration.

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 X-Bow R is built for purpose in the most wonderful of ways. From the visible suspension components to the rocket-style exhausts, to the stripped-bare interior, it's fairly obvious that form came a distant second to function in the X-Bow's design process.

And, for us at least, that's a tremendous thing. It looks raw and visceral, and a bit like Harvey Dent post-fire - you can see all the normally hidden components doing their thing. It's mesmerising.

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.

Short answer? It's not. People are unlikely to test drive an X-Bow R and start looking for cupholders and storage space, but if they did, it wouldn't take long.

Aside from the twin seats, a four-point racing harness, a high-mounted gearshift, a pull-lever handbrake, and detachable steering wheel, the cabin is as bare as Old Mother Hubbard's cupboard.

Luggage space is limited to what you can carry in your pockets (though wearing cargo pants will help) and even getting in and out of the thing takes some fleet-footed antics. With no doors you need to literally jump in. And the side sills are only rated to 120kg, so heavier types will need to avoid stepping on them at all, and instead attempt a kind of running leap into the cockpit.

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.

The X-Bow R's power comes from an Audi-sourced, turbocharged 2.0-litre engine, paired with a VW Group six-speed manual transmission (and one of the stubbiest gearsticks in existence). That mid-mounted marvel produces 220kW at 6300rpm and 400Nm at 3300rpm, and ships it off to the rear tyres with the assistance of a Drexler mechanical limited-slip differential.

Thanks to its lithe and lightweight body, that's enough to propel the X-Bow R from 0-100km/h in a blistering 3.9 seconds, and on to a top speed of 230km/h.

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.

KTM lists the X-Bow R's claimed/combined fuel figure at 8.3 litres per hundred kilometres (though we were managing mid-12s after an, ahem, very spirited test), with emissions pegged at 189 grams per kilometre.

The X-Bow R is also fitted with a 40-litre fuel tank, accessed via a side-mounted inlet. Instead of a fuel gauge, expect a digital reading showing how many litres you have left.

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.

It couldn't be more Fast and Furious if it had Vin Diesel growling under its (non-existent) bonnet. We have technically driven faster cars, but we have never driven anything that feels quite so fast as this utterly insane X-Bow R.

Climb in, strap into the four-point harness and select first via the surprisingly easy-to-manage gearbox and clutch set up, and, at slow speeds, wrestle with the dead weight of the completely unassisted steering, and it's immediately clear that this is a driving experience like nothing else currently road-legal in Australia. Even at walking pace, the X-Bow R feels poised for an assault on the future, and it attracts attention on the road like nothing else we've ever driven.

Its road-scraping ride height and diminutive dimensions make tackling traffic an intimidating prospect, with regular hatchbacks suddenly taking on truck-like proportions and actual trucks now looking like passing planets. There's a constant concern that you're sitting well below the traditional blind spot, and that you could be crushed at any moment.

Combine all that with the bad weather that cursed our final day of testing, and the X-Bow R is all sorts of watery hell. It is truly homicidal in the wet, too, with the back end breaking grip at the slightest provocation. And the turbocharged 2.0-litre offers plenty of that.

But on a sunny day, and on the right road, it's pure driving bliss. The acceleration is brutal, the grip endless and the Audi sourced gearbox an absolute treat. And it pulls in every gear, tackling 35km/h corners in third and absolutely blasting out the other side.

Cornering is scalpel sharp, and the steering - so heavy at slow speeds - is light and efficient at pace, requiring only the most minuscule of movements to bite into a bend.

It is anything but perfect in the city, and even a light sprinkling of rain will have you seeking shelter (and a refund), but on the right road, on the right day, there are few if any cars that offer the kind of razor-sharp thrills and intoxicating excitement of KTM's monstrous X-Bow R.

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.

The X-Bow R is covered by a two-year, unlimited-kilometre warranty, and while service prices aren't capped, Simply Sports Cars estimates an average serve cost at about $350.

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.