BMW 540i vs BMW Alpina B4

What's the difference?

Not all superheroes wear capes, and we're proud to report the 530e does its bit for green motoring without feeling the need to shout about it. And with no price or specification penalty, it's easier being green than ever before, and the pricing of this BMW really puts the cat amongst the canaries.

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.

Crucially, there's nothing weird about the way the 530e looks. While some green cars look like they've been designed by one of the kids from 3rd Rock from the Sun, the 530e looks much the same as the rest of the range, save a few tiny but telltale giveaways - like the e-drive badging outside, and what looks like a bonus fuel flap tucked in behind a front wheel that houses the whole plug-in bit.

And we really, really like it. It's elegant and statesman-like from every angle, and looked especially important in the deep-blue colour of our test vehicle. It's not over-designed, with body creases used sparingly, and the occasional glint of polished silver that rings the windows and the grille adds a final sense of shininess to an understated design. 

Inside, there's more going on than you might normally find in a BMW. The hugely complicated digital display screen now includes everything from battery charge, power usage to the usual assortment of speedometers and petrol readouts. 

It doesn't feel overdone or crazily festooned, but there's more at play here than in your usual BMW.

The dash is busy, too, with a wide screen emerging from a centre stack that also houses a CD player and a digital aircon setup, which in turn sits above a complex centre console from which you can alter driving settings, control the multimedia or cycle through electric modes. It doesn't feel overdone or crazily festooned, but there's more at play here than in your usual BMW.

Elsewhere inside, the seats are beautifully designed, with a quilted leather highlight through the middle, while the gloss-black strip that lines the dash hides a dual strip of ambient interior lights that also runs across all four doors.

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.

As the world's motoring tastes shrink faster than a lap-banded Clive Palmer, it's easy to forget the joys of the full-size sedan, but the space for passengers and luggage in the 5 Series will have you questioning your downsizing ways.

Upfront, there's plenty of room between front-seat riders, who will also share two smallish cup holders, along with room in each front door for bottles. There's also a dedicated wireless charge pad (which, because of its tight design, is crazy difficult to actually remove your phone from), but you'll also get two USB points and a power outlet that's hidden in the sizeable centre storage bin as standard fit.

Backseat riders get heaps of space, both in width and in leg room behind the front seats. And there's twin air-con temp controls and twin power outlets, too. But middle-seat passengers will be forced to sit with their legs on either side of the raised tunnel, which will definitely impact on comfort.

The boot's still sizeable, despite shrinking slightly to house the battery/fuel tank setup

Best to ditch the fifth passenger, then, and deploy the pull-down seat divider, which also houses two cup holders. Finally, there are three ISOFIX attachment points, one for each seat in the back.

The boot's still sizeable, despite shrinking slightly to house the battery/fuel tank setup (the tank has been moved further back to accomodate the batteries), and can be adjusted to be a flat load area if you'd like, offering up to 410 litres with the rear seats in place.

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.

Drift around in pure EV mode and you'll be relying on the 530e's 83kW and 250Nm electric motor, which will provide what BMW refers to as "between 28 and 32 real-world kilometres".

Run out of range, or simply use too much throttle, and the 2.0-litre petrol engine comes into play, adding 135kW and 320Nm to the mix. All up, that's 185kW and 420Nm - respectable numbers by any measure, and enough to match the petrol-powered 530i's zero to 100km/h sprint of 6.2 seconds.

That power is fed through an eight-speed automatic transmission before being sent exclusively to the rear wheels, where it belongs.

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.

Like a Facebook relationship status, it's complicated. The 530e will sip a claimed combined 2.3 litres per hundred kilometres on the claimed/combined cycle, which is amazing for a car this size. Better still, it seems genuinely achievable - at the vehicle's launch, our own Richard Berry recorded a stunning 2.0 litres per hundred kilometres on a short test route.

But that's with a full load of battery charge on board. For our week with the 530e we were unable to actually plug it in (living in Sydney, I can't afford a garage), so once the initial battery charge had been used we were back to mostly petrol power. Unlike some other plug-in hybrids we've driven, we found it very difficult to recharge the battery to any meaningful level using regenerative braking, so once we were flat we stayed flat. If we had plugged it in, it would have been a two-hour recharge using a specialised wall unit, or about four hours using a normal plug.

As a result, though, our fuel use was closer to 7.0 litres per hundred kilometres after some considerable real-world testing.

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.

There's so much to like about the way the 530e sets about saving the world, and that's mostly because it doesn't shout about it, either to the driver or the outside world.

It's very much an underpants inside its pants superhero, which makes us like it even more. Set off in EV mode, and the 530e will drift silently away from the curb, burning battery power over fuel for as many as 30(ish) kilometres. But equally important, the shift from green to gas is largely imperceptible, with the petrol engine joining in willingly when you ask it to - usual via a prod of your right foot.

It is so effortlessly smooth that you need to really pay attention to notice the eight-speed 'box changing gears at city speeds, and it's commendably quiet, whichever drive mode you're in.

Downsides? Well, it doesn't feel quite as sharp as it's conventional-engined siblings. The batteries add around 230kg in weight, which never helps, and it all feels a little softer and a little less dynamic, even with Sport mode engaged. BMW assures us the adaptive suspension setup and tune is identical, but the 530e feels noticeably softer when you tackle a twisting back road. And that encourages you to use your right foot a little more, which in turn negates the whole electric thing in the first place.

One of the great joys of BMWs has always been their ability to transform from cosseting comfort to rear-drive rocket when you want them to, and you can't help but notice the 530e isn't quite up to that challenge. But if your intentions are mostly city- and freeway-based, then this plug-in BMW is almost indiscernible from its petrol-powered sibling.

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.

Like the rest of the 5 Series range, the 530e falls under BMW's three-year, unlimited-kilometre warranty. There are no set service intervals, either, with BMW using what it calls 'condition-based' servicing. In other words, the car will tell you when it requires a trip to the service centre.

The batteries are covered by a separate warranty covering six years or 100,000km.

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.