• The Art of Deception AC Schnitzer knows a thing or two about suspension as witnessed by its setup for the M4. The M4 is developing a reputation for being a little bit of a handful in slippery conditions, so does it really need more horsepower and other upgrades? Words: Adam Towler. Photography: Gus Gregory. #AC-Schnitzer-ACS4-Sport / #AC-Schnitzer-ACS4-Sport-F82 / #S55B30 / #S55B30-AC-Schnitzer / #AC-Schnitzer / #2015 / #AC-Schnitzer-ACS4-Sport / #BMW-M4-F82 / #BMW-M4 / #AC-Schnitzer-F82 / #BMW-M4-AC-Schnitzer / #BMW / #BMW-4-Series / #2016

    It’s quite likely that many readers of this magazine believe the BMW M4 is the finest incarnation of the mid-size German sports coupé yet built. However, it can’t be denied that amongst the car-loving community at large, the M4 has split opinion. No one questions whether its performance is adequate, or for that matter superlative; I can’t give you an exact figure off the cuff but I’m sure it completely demolishes something like an old E46 M3 around a certain German racing circuit, and many others, too.

    Let’s consider, though, some of the more esoteric elements of the M4 proposition. The power increase over the old E92 M3 is actually only marginal – an extra 11hp taking it to 431hp – so it’s the torque that’s making the difference, all 406lb ft of the stuff versus the 295lb ft from the naturally aspirated V8. And that’s not all. Forget for a moment the peak difference and consider where that number is now developed: it’s from as little as 1850rpm and is then held all the way to 5500rpm in one arrow-straight line. In one of the older V8s the engine needed to be turning at 3900rpm before the full 295lb ft came on stream. Quite simply, whenever you plant your foot in an M4, as long as the engine is working at more than a whisper above idle speed, things happen… and they happen fast. Gear choice is vastly less critical, and while I won’t get into the highbrow discussions of whether it has become all too easy and the loss of that gorgeous soundtrack, there’s no denying that on modern, crowded roads, the S55 engine’s on-demand haymaker is exceedingly effective.

    This sheer grunt does give the M4’s chassis something to really think about. On a smooth, dry surface the car is hugely effective, with EDC damping allowing for a fairly comfortable ride or ruthless body control at the press of a button. But on a cold, greasy, wintry B-road with all the irregularities in surface that are to be expected, it’s a car that can really bite the unwary. Left in the standard setting, the suspension can struggle to contain the torque if deployed clumsily, and sudden crests can make the car very lively indeed. I could probably add that the rather muted steering in the modern style doesn’t assist the challenge, either. In such a situation, you either spend a good deal of your time watching the yellow traction control light flicker incessantly, which is very frustrating, or DSC is switched off whereupon you’re really juggling with the steak knives set.


    That’s where this Schnitzer ACS4 comes in. I know, it doesn’t look like it’ll be the answer to this particular problem. Despite keeping an open mind the additional ‘aero’, tuner-style 20-inch rims, lowered ride height, talk of coilovers, plus a comically noisy exhaust threatens to overwhelm me with preconceptions of a negative kind. A ‘slammed’ aftermarket treatment might be the last thing this car needs.

    Then there’s the news that really sets the alarm bells ringing: peak power on this M4 has been raised to a massive 510hp. Whatever you say about the new turbo power generation, that’s a figure that any M3 driver just ten years ago would have thought impossible. Moreover, the maximum torque now stands at 479lb ft, which threatens to really give the rear axle something to get in a flap about.


    I travel to Schnitzer’s UK importer, Rossiters, near Kings Lynn, to collect the Austin yellow demo car, mine for a few days. Rossiters held the franchise before BMW made things official in the late 1990s, and then picked up the reins ten years later when BMW UK ended that arrangement. Today, you can order Schnitzer parts in 40 of the UK’s BMW main dealers, as well as 20 other non-franchise BMW specialists. This demo car features plenty of the Schnitzer goodies on offer: there’s the engine upgrade, which I’ll come onto in a minute, with a new engine cover for added artistic embellishment; the carbon fibre front spoiler elements, ‘canards’ either side of the nose and carbon rear diffuser (no aerodynamic advantage is implied or given); the ‘RS’ suspension kit; ‘export version’ sports silencer; Type V forged 20-inch rims with Michelin Pilot Super Sport tyres (255/30 R20 front and 275/30 R20 rear); a fancy pedal set; and some stickers for the exterior. All in that’s £20,081.61 added to the price of your M4, including fitting. Let’s see if it’s worth it.


    The most exciting snippet of information I gather from talking to Chris Rossiter and Lorcan Parnell at AC Schnitzer UK is that their colleagues back in Germany have developed this kit over many miles of road testing, and that their mantra is ‘better fast not hard’ (stop sniggering at the back please). In addition, the finer points of the setup have been tweaked after driving on the lanes close to Rossiters’ Norfolk workshop. This attention to what matters in a road car and not a pursuit of lap times bodes very well already. Such thoughts momentarily leave my mind when the ACS4 fires up with a boom and idles angrily. The cat-back exhaust keeps the factory valving system, but when they’re open – especially on cold-start – it is mercurially loud.


    The modifications to the engine consist solely of altering the messages from the ECU. Schnitzer achieves this not by remapping what’s already there, but by fitting a ‘piggyback’ second ECU that adjusts the electronic information accordingly. It claims that the achieved outputs remain inside the limitations of the gearbox, and it supplies the car with a twoyear/ 60,000km warranty that sits alongside the regular BMW warranty for the car. This can be extended to three years for an additional £1082.02. Quite rightly, Rossiters feel this peace of mind elevates the conversion above some of the straightforward remaps out there.

    It may well have over 500hp but that’s not what is grabbing my attention at the moment. Leaving the small town of Dersingham it’s the ACS4’s low speed ride that I’m most aware of. With such low profile rubber fitted it’s no great surprise that the car picks out every last little bump on the road, which makes for a busy experience. This coilover option is the third and highest level of modification offered by Schnitzer for the M4, and forsakes the factory EDC dampers for a passive setup that is nonetheless adjustable manually for rebound, compression and ride height.


    Fairly soon we’re beyond the limits of the town and the speeds inevitably increase, whereupon it occurs to me that the jostling has petered out considerably. During my time with the car I become obsessed with this aspect of the ACS4: there are occasions when I think it’s too busy, and on a particular surface that it doesn’t like – one busy dual carriageway springs to mind – it seems to make a meal of a road that I’d never thought that bad. But overall I sense that while the suspension is working hard, it does filter out the worst of the movements entering the cabin. It sounds worse than it is: the intrusions banging through the M4’s structure and causing the odd rattle here and there, but my head isn’t nodding against my chest and my wobbly bits aren’t being, er, wobbly. I learn to live with it, and soon accept it as ‘normal’.

    The faster your drive the ACS4, the better it gets. And going fast is one thing this car does very well indeed. The sheer rate of acceleration is now shocking. It’s easy to get into the mindset where you work the engine between 2000-4000rpm and can’t imagine going much quicker. Then an odd occasion presents itself where the engine can really be wrung out to the redline and it’s simply biblically fast. Or at least it is when it can find traction. In the middle of winter, that isn’t all that often, it must be said.


    This is where the Schnitzer bits really shine. I find it most refreshing that the damper setting on the dash can be ignored, primarily because it’s one less thing to meddle with on the move. The real advantage is that as a driver, you learn the car, get to know how it will react in certain situations and under certain provocations. There’s something really straightforward about this car which, if you switch the DSC systems off partially or completely, means it’s nowhere near as scary as a 500hp coupé should be. Compressions and crests don’t hold any fear for the Schnitzer driver, the ACS4 piercing through them without any of the unsettling behaviour of the standard car, and even the steering seems to have gained a little more feedback, tugging slightly this way and that depending on the road’s surface.

    The ACS4 likes to go sideways, usually at every opportunity. This is one of those cars that can be made to lose traction at the rear almost at will, but once you’ve got a handle on what happens next it is surprisingly controllable. Time and again the big yellow 4 Series has me giggling with euphoric nervousness at having kept things facing in the right direction, but the control once the tail has swung around is just lovely, and it’s a great feeling to have it all hooked up on the exit of a corner just on the cusp of wheelspin. If anything, the ACS4 makes 500hp seem more manageable at times than the standard car’s 431hp. It’s worth saying, though, however obvious, that it would be foolish to treat this M4 as if it were a grownup Mazda MX5. If there’s one thing you’re always aware of, even when having a lot of fun, is that it is an inherently overpowered, rear-drive car that’s tractionlimited in bad weather. It’s unwise to take too many liberties with any 500hp+ car, however progressive it seems most of the time. An aural indication of this is the snort released through the quad tailpipes when you lift suddenly off the throttle under full boost. It’s an ugly kind of noise, akin to a lightning bolt cracking through the atmosphere, and it adds to the impression that this is one bad car to know.


    By the end of my time with this M4 it has really got under my skin. I’ve really enjoyed its transparency in a modern car market obsessed with modes and button pressing. Left in the normal drivetrain setting it’s a more refined proposition without the fake engine ‘noise’ (I think the straight-six sounds nice just as it is to be honest), and the benefits that the suspension bring to the body control and predictability of the chassis in extremis are really appealing. I’d do without the body addenda, although that may well be at the top of your list – these things are, of course, down to personal preference. I’d forsake the wheels, mainly because I’d love to try this car on standard 19-inch wheels fitted with tyres that have a larger sidewall to see what the ride and road noise were like then. The engine upgrade is one of those mods that once experienced there is simply no going back, and given it’s under a warranty I don’t think I could say ‘no’. I could drone on for paragraphs about how rapid this car now feels, but it’s something that has to be experienced to be believed in truth: it never, ever, feels dull. I’d leave the exhaust though, ostensibly to stay a bit more ‘under the radar’, and anyway, there are no performance claims made for it either. In other words, just taking the engine and suspension options adds around £7000 to an M4, and given the performance and dynamic benefits they bring, that seems like a very good deal to me. Sometimes, appearances can be deceptive.

    CONTACT: AC Schnitzer UK / Tel: 01485 542000 Website: www.ac-schnitzer.co.uk

    TECH DATA AC #Schnitzer ACS4 Sport

    ENGINE: Twin-turbo, straight-six
    CAPACITY: 2979cc
    MAX POWER: 510hp
    MAX TORQUE: 476lb ft
    0-62MPH: 4.0 seconds
    50-120MPH: 6.2 seconds
    TOP SPEED: 155mph (limited)

    MODIFICATIONS:

    ENGINE: AC Schnitzer performance upgrade: £3641.04; engine optics package: £378.73; optional third year warranty: £1082.02

    EXHAUST: Quad sports exhaust system (export version) with black tailpipes: £3275.75

    WHEELS & TYRES: AC Schnitzer Type V lightweight forged alloy wheels with Michelin Pilot Super Sport tyres. Front: 9x20-inches with 255/30 R20 tyres. Rear: 10x20-inches with 275/30 R20 tyres: £5949.66 (including wheel bolts and RDC tyre pressure valves)

    SUSPENSION: AC Schnitzer RS adjustable suspension package: £3473.75; wheel alignment: £144

    STYLING: AC Schnitzer carbon fibre ‘canards’: £960.50; carbon fibre front spoiler: £1050.26; carbon fibre rear diffuser: £1319.50

    INTERIOR: AC Schnitzer aluminium pedal set: £195.60 All prices quoted include parts, labour and VAT

    I’ve really enjoyed its transparency in a modern car market obsessed with modes and button pressing.


    It might look pretty standard in the interior from the driver’s seat, but the driving experience is anything but standard!
    • How fast? Looking at your performance figures for the AC Schnitzer ACS4 Sport I have to assume there is an error regarding the 50-120mph time? Unless How fast? Looking at your performance figures for the AC Schnitzer ACS4 Sport I have to assume there is an error regarding the 50-120mph time? Unless it’s rocket-powered it would have to be 16.2 seconds rather than 6.2? If not, then that means a 0-120mph time of less than ten seconds?!  More ...
    • While we haven’t independently verified AC Schnitzer’s figures Chris, we have no reason to doubt them; even in its standard form the M4 is a staggerinWhile we haven’t independently verified AC Schnitzer’s figures Chris, we have no reason to doubt them; even in its standard form the M4 is a staggeringly quick machine! Schnitzer tested the standard car through this speed increment (80-180km/h, which equates to 50-120mph) and recorded a time of 7.9 seconds, so with 80hp more we wouldn’t be surprised if Schnitzer’s ACS4 Sport was indeed that fast.

      It is an unusual increment to time, but if one has a look at quarter-mile times for the M4 many magazines have posted pretty impressive figures for the standard car. Car and Driver recorded a 0-100mph time of 8.6 seconds for an M4 on its way to a 12.1-second quarter-mile time with a terminal velocity of 119mph. With the additional power and torque of the Schnitzer car we reckon it’s probably just about spot-on.

      The bottom line is that cars these days are hugely faster than they used to be!
        More ...