BMW M4 GTS v M3 CSL 2017 Comparison

Some say the limited-edition E46 M3 CSL is the finest M-car BMW has produced. Staying true to the hallowed M3 breed, it was the last to be powered by a naturally-aspirated straight six, continuing the tradition of every M3 dating back not quite to the original E30 four-cylinder of 1985, but the E36 of 1992.

In these modern turbocharged times, the M3 CSL remains a symbol of pure, unadulterated, responsive and high-revving BMW M performance. So where does that leave its spiritual successor, the ferocious, racetrack-ready M4 GTS – the quickest and most hard-core BMW road car currently available? Let's find out.

Long before Mercedes-AMG and Audi Sport employed V8 power to upset the status quo, BMW’s M3 with its naturally-aspirated straight-six engine - the quintessential M-car in the days before the Bavarian brand built the M2, M4, M5, M6, X5M and X6M - ruled the mid-size German sports coupe roost.

BMW did join the bent-eight party with its 4.0-litre V8-powered E92 M3 of 2007, and then broke another promise with its first turbocharged M3 in the F80 of 2014.

But most agree the finest M-car was the E46 M3 which debuted in 2000.

BMW was so confident its replacement for the lauded E36 M3 lifted the bar in every measurable way that, for the launch of the E46 M3 at Eastern Creek Raceway (now Sydney Motorsport Park), the company took the unusual step of bringing along its predecessor for back-to-back testing.

Sure enough, despite adding significantly more weight, the larger, wider, higher-tech and more powerful 3.2-litre E46 smoked the old E36 in a straight line, on the track and around a slalom course in the wet and dry.

Brandishing far more mechanical grip and the M3's first use of electronic stability control, the E46 not only delivered a far greater performance envelope, it was also a doddle to drive much faster.

Then came the stripped-out, beefed-up, track-focussed limited-edition CSL, raising the bar again and creating a BMW performance icon many still regard as Munich’s finest ever M-car.

Six of the best
The legend of the CSL – which stands for Coupe Sport Lightweight – exists for good reason. At a time when the standard M3 still weighed less than 1500kg, after a ruthless weight-reduction program, the CSL slashed a significant 110kg. Gone was much of the sound deadening, electric front seat adjustment, the satellite navigation, air-conditioning and CD/radio, although the last two remained no-cost retro-fit options.

Carbon-reinforced polymer replaced the steel body panels and the rear window was replaced with thinner glass. And here’s crystal-clear BMW M focus for you: Ditching the steel roof and replacing it with a carbon-reinforced plastic version not only pared 7kg, it also lowered the centre of gravity and increased body rigidity.

All-up, the M3 CSL’s tare weight was just 1385kg and it retained the standard M3’s ideal 50/50 front/rear weight distribution.

Then BMW set to work on the CSL chassis, fitting specific race springs and dampers, a tighter steering ratio (14.5:1 v 15.4:1), larger floating front brake discs and bigger rear brake calipers. And the ESC was re-tuned to include a broader activation threshold in ‘M track mode’.

Exterior modifications for the CSL extended to lightweight 19-inch cast BBS alloy wheels fitted with semi-slick Michelin Pilot Sport Cup tyres, and an aerodynamic package including a carbon-fibre front bumper/splitter to boost high-speed downforce by up to 50 per cent, a carbon rear diffuser and a new bootlid with an integrated lip spoiler.

Inside, there were fibreglass race bucket seats up-front, fibreglass-backed rear seats and carbon-fibre for the centre console, door inners and headlining. The driver scored a new steering wheel which jettisoned the standard M3’s audio, cruise control and telephone controls and replaced them with the single M button.

Even the boot floor was preplaced by fibre-board.

At the heart of the M3 CSL was BMW’s naturally-aspirated 3.2-litre S54 straight-six engine, in this case uprated to 265kW and 370Nm (up 13kW and 5Nm) thanks to lumpier camshafts, new exhaust valves, bigger air intake with a carbon manifold and a revised exhaust manifold.

BMW’s final - and finest - atmo six was hooked up exclusively to the company’s SMG II transmission in the CSL (the standard M3’s six-speed Getrag manual was unavailable).

Essentially a single-clutch version of today’s dual-clutch automated manual gearboxes, it featured a Formula 1-style electrohydraulically actuated (single) clutch, plus a more advanced ‘Drivelogic’ software package which allowed it to shift faster than the regular M3 (0.08sec).

With a 5.2kW/kg power-to-weight ratio, the M3 CSL was claimed to hit 100km/h in 4.9 sec on its way to a 250km/h-limited top speed.

Unavailable in North America and produced only in two paint colours – Silver Grey Metallic and Black Sapphire Metallic – the CSL was priced at a heady $210,000 Down Under back in 2003.

In a highly profitable exercise for BMW, which built more than 85,500 E46 M3s in total, just 1400 CSLs were made in Regensburg, Germany and only 23 of them came to Australia, where owners are currently asking up to $140,000 for top-condition, low-mileage examples.

Needless to say, with just 13,000km under its belt, the pristine silver CSL you see here is one of the best around and convincing BMW Australia to let us flog its pride and joy wasn’t easy.

A new benchmark
Fast-forward more than a dozen years and the modern-day equivalent of the M3 CSL is the M4 GTS (thanks in part to the renaming of the M3 coupe as the M4 for the current F82 generation released in 2014).

Just as the CSL moniker was used before (just once, on the 1972 E9 3.0 CSL - a lighter and more powerful version of the pretty 3.0 CS coupe), there was also a GTS version of the previous E92 M3, powered by a monster 4.4-litre V8.

But BMW’s newest GTS also happens to be the quickest and most hard-core road car it has produced, as well as the quickest M4 this side of the track-only M4 GT4 racer (the upcoming M4 CS will be more road-focussed, hence the lack of an L in its name).

Its pace comes partly from a world-first water-cooled turbocharger system allowing higher boost pressure, which increases maximum power from 317kW to 368kW (500hp in the old money) and peak torque from 550Nm to a brawny 600Nm – seriously big numbers for a six-cylinder.

The M guys also gave the CSL a weight reduction program, paring a modest 30kg (although fitting the optional carbon-fibre wheels almost doubles that number). The numerical results are a 1472kg tare weight, 0-100km/h in a claimed 3.8sec and a top speed of 305km/h.

Yes, undercutting its donor model by three-tenths also makes the M4 GTS quicker than any other BMW production car - including the M2, M3 Competition, M5 and M’s next-quickest model, the near-$300K M6 (3.9sec).

The secret to the wildest M4’s pace – both in a straight line and around corners – is not just its prodigious power and relatively light weight, but a track-honed chassis which maximises traction.

Designed to demonstrate what’s possible with a road-legal vehicle when racetrack performance is the priority, the GTS is dripping with race technology.

Its chassis rolls on motorsport-spec, three-way adjustable coil-over M suspension with thicker anti-roll bars and a rigid connection between the rear axle subframe and body (no rubber bushings).

And its 19-inch front and 20-inch rear wheels with sticky Michelin Pilot Sport Cup 2 tyres are retarded by carbon-ceramic brakes with six-piston front calipers.

Weight-saving is everywhere, from the carbon-reinforced body panels, aluminium suspension parts and titanium exhaust, to the omission of the rear seats, front audio speakers, spare wheel and sound deadening.

Inside, there’s a pair of hard-core, fixed-back carbon race bucket seats with harnesses, an acid-orange highlighted half roll cage and the ability to individually tune the engine, steering and seven-speed dual-clutch gearbox.

All of this is wrapped in body adorned with an aggressive body kit punctuated by a massive adjustable rear wing and also featuring an extendable front splitter.

Only 700 M4 GTS cars were built globally, just 25 of which made it Down Under last year. Despite a sticker price of almost $295,000, making it one of the priciest M-cars ever, almost all had confirmed buyers even before the model was confirmed for Australian sale.

Chalk and cheese
In its day, the M3 CSL was one of the world’s quickest, sharpest and most exhilarating vehicles, making it one of our all-time favourite performance cars.

But time marches on and, from behind the Alcantara-trimmed steering wheel - even in isolation - it now seems creaky, fragile and old-school.

The CSL’s non-adjustable suspension feels brittle on any road surface apart from smooth racetrack hotmix - even firmer than the GTS-branded M4’s - transmitting shockwaves throughout its body and dated interior (although noise levels inside the CSL were actually lower).

Other than its centre console-mounted window/mirror switches, a Sport button, DSC switch and SMG gearchange adjuster, you notice a scarcity of electronics. There’s no electric hand brake, no suspension adjustment and none of the mod-cons we’ve come to expect, like one-touch indicators let alone advanced driver safety aids.

Sitting in the CSL’s carbon and Alcantara-lined cabin, it feels closer in size to the M2 than the M4, which has much bigger window openings and therefore superior outward vision.

The only adjustment for its one-piece race bucket seats - which are positioned much further forward in the cabin than the M4 - is a manual slide function, meaning they don’t fit all shapes and sizes.

And while its mechanical hydraulic steering is delightfully full of feel, feedback, precision and unfettered by any unwanted interference, it now feels way too light in a straight line and never as communicative as the electric steering in the GTS.

But what an engine. Offering instant response from any revs and spinning freely to beyond 8000rpm, the CSL’s glorious atmo six delivers a raspy, spine-tingling engine and exhaust note which evokes fond memories of past M-cars.

Exploiting its generous torque delivery and even broader power band is child’s play thanks to that pure, unfiltered steering, lack of body roll and less intrusive stability control system.

The CSL allows a sizeable dose of oversteer before intervening seamlessly, making it a thoroughly enjoyable drive on any smooth, winding road.

In terms of the CSL’s biggest technical shortcoming, the culprit is that awful SMG transmission. Frustratingly slow when left to its own devices, violently abrupt in full-noise manual mode and, when using the paddle shifters, always requiring plenty of anticipation, it is without doubt the CSL’s Achilles heel.

In contrast, the GTS M4’s dual-clutch unit is quicker, smoother, smarter and far more effective at transferring 230Nm more torque and over 100kW more power to the rear wheels…making for violent acceleration in any gear.

Yes, the M4’s tyre noise – especially at the rear, where there’s zero wheelhouse lining – is over the top, the oversize wing obscures rear vision, its high-sided seats and race harnesses are a pain to live with and the car we drove even served up an annoying rattle in the top of the dashboard.

But if the CSL’s chassis responses are pin-sharp, then the GTS’s are scalpel-like, with better weighted steering and slightly more compliant suspension giving it more accuracy and delivering an even tighter connection between road and driver - notwithstanding its extra weight, electric steering and turbocharged engine.

And if the CSL’s engine is violent and the regular M4’s twin-turbo straight six vicious, then the GTS’s fettled turbo six is a mass-murderer, thanks to a brutal top-end rush towards its 7600rpm limiter.

Unsurprisingly, the newer car was considerably quicker around the Wodonga TAFE’s short but fast DECA circuit (despite the overly sensitive ESC, which would activate even at 140km/h in a straight line) and pretty much everywhere on a rough, country-road loop.

In fact, the M4 GTS was almost two seconds quicker than any other BMW M model we’ve tested at DECA, including the M2, M3 30 Years, M5 and M6.

By contrast, the M3 CSL was the slowest, trailing even the M240i and X6 M, and lapping almost 4sec slower than the GTS, which is also far more efficient.

Clearly illustrating the 13 years of development and three model generations which separate it from the GTS, the CSL’s 0-100 deficit feels much bigger than the 1.1 seconds BMW claims.

And let’s face it, 4.9 seconds is far from quick these days, when a Volvo S60 sports sedan can eclipse the CSL on its way to Australia’s national speed limit.

That said, the M3 CSL’s sharp, unadulterated chassis and engine make it a superbly balanced, enjoyable, accessible and reasonably rapid performance car which is still a joy to drive at the limit.

Sure, the finest and purest M3 ever was way ahead of its time, but the M4 GTS is better in every aspect and demonstrates just how far BMW’s road car technology has come, even if this road-legal race car may actually intimidate some.

Both of these mid-size BMW M coupes are the finest examples of their respective breeds and destined to be classics, but there’s absolutely no doubt the M4 GTS is the new M benchmark.

2017 BMW M4 GTS pricing and specifications:
Price: $294,715 (plus on-road costs)
Engine: 3.0-litre twin-turbo petrol inline six-cylinder
Output: 368kW/600Nm
Transmission: Seven-speed dual-clutch automatic
Fuel: 8.5L/100km (ADR Combined)
CO2: 199g/km (ADR Combined)
Top speed: 305km/h
0-100km/h: 3.8sec
Safety rating: N/A

2003 BMW M3 CSL pricing and specifications:
Price: $210,000 plus ORCs (when new)
Engine: 3.2-litre inline six-cylinder
Output: 265kW/370Nm
Transmission: Six-speed sequential automatic
Fuel: 11.0L/100km (ADR Combined)
CO2: 287g/km (ADR Combined)
Top speed: 250km/h
0-100kmh: 4.9sec
Safety rating: N/A