Mercedes SLK vs BMW Z4

For lovers of roadsters, the BMW Z4 and Mercedes SLK represent dream machines. But which one truly makes your fantasies come true?

Published On Oct 30, 2012 08:24:00 PM

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Now if someone was in the market for a powerhorse. An impractical beast which oozes style, performance and sheer thrill. Then with 300-plus bhp under your right foot and the wind in your hair, the BMW Z4 and the Mercedes-Benz SLK are the perfect machines to transport you to a different reality. But India – with bus passengers spitting out of windows, goods trucks spewing bits of cargo at random and rickshaws letting out noxious kerosene fumes – is not the ideal place to drive a convertible.

Fortunately, the carmakers spared some thought and the Z4 and the SLK come with folding metal roofs. You can go from the carefree charm of a convertible to the security of a coupé in under half a minute. At the touch of a button.

But these cars aren’t for everyone. They’re for people who already have all the practical cars they need and don’t mind spending the better part of Rs 70 lakh for a bit of flair, two seats and a healthy dose of power.

Both are quick, quite sporty and the sounds that their respective quad exhaust pipes make when provoked would have any motorhead’s heart racing. But neither holds a Nürburgring lap-record. It’s this middle ground between the hardcore sportscar and luxo-mobile that makes these two more appealing and usable. But which one is better? We pick a warm overcast day to find out.  

CROWD PULLERS

We start at a local five-star and it’s clear from the crowd milling around that the Z4 is the more attractive one. Its long silhouette, mean-looking hooded brows, the super-wide ‘V’ on the bonnet and the gorgeous skinning gives the car an almost exotic air. Unfortunately, put the curved roof up and half the charm is lost, taking quite a bit away from the edgy styling of the rest of the car.

The SLK on the other hand, looks much better with the roof up. In fact, the Merc is full of strong, slack-jawed lines. Like the Z4, it’s got the classic long hood and short boot stance, but the SLS-style front grille and the muscular rear give it great poise, and the flared wheel arches give it plenty of presence.

Round one is a BMW victory. But by a small margin, decided mainly by the onlookers.

MOTOR MATTERS

The cars are similar on the scale with the Z4 at 1525kg and the SLK at a slightly heavier 1540kg. Also similar are the power figures for both vehicles, with performance not differing by much, at least up to 120kph.

At 100kph, there’s just a hair’s breadth between the two and the gap widens significantly only after you power on past 150kph. Most of this is down to the tech under their respective bonnets.

The Z4’s 3.0-litre straight-six motor features BMW’s infinitely variable Valvetronic system, direct-injection and a high-tech twin-scroll turbocharger. Caress the throttle and the motor feels as smooth and as well balanced as only a straight-six can. But flatten the accelerator after you’ve made sure you have a big enough gap ahead of you and the twin-clutch gearbox snaps the motor to attention, the tachometer needle popping up like a jack-in-the-box. Acceleration from rest is one seamless rush. Nought to 100kph takes a very scant 6.1 seconds. Keep the throttle pinned down for another six seconds and you’ll snarl past 150kph! The pace is extremely satisfying, and thanks to the turbo-induced torque, you don’t have to really wring the engine out to go fast – you go from a cruising speed of 110kph to 150kph in under seven seconds if you flatten the throttle.

The Z4 also has a launch control mode – hold the car on the brakes, crush the throttle pedal to the floor, wait till the revs build up and jump off the brakes. The seven-speed gearbox dumps the clutch and you’re shot down the road with a very satisfying scream and two long strips of tortured rubber.

The SLK, on the other hand, relies on displacement. Its larger, 3.5-litre naturally aspirated motor makes slightly more power than the Z4’s 3.0-litre motor, but peak torque of 37.7kgm is not as much as the BMW’s 40.8kgm (the Z4 engine has the longer stroke). Nevertheless, thanks to the torque curve peaking at 1500rpm, throttle response is instant and every jab on the throttle has satisfying results. The SLK’s seven-speed torque converter auto ’box is pretty obedient and responsive to paddleshift inputs, but is still nowhere as quick as the dual-clutch unit on the Z4. For most situations, performance is right up there with the Z4 and the engine is both free-revving and flexible. The motor pulls cleanly and very linearly to the redline. It may not have that ballistic top-end that a BMW in-line six is famed for, but the fantastic mid-range more than makes up for this. The thing is, it’s so linear that you sometimes forget how fast you are going – it’ll sneak up on 180kph when you’re not paying attention and then sidle up to 220kph if you hold on to the throttle for a tad more.

When driven flat-out, the SLK350 will hit a 100kph in just 6.4 seconds, breach 200kph in an equally impressive 25.52 seconds and slam into the speed limiter at 250kph. The noise it makes is also fantastic, right from the crackle at start-up to the snarl when you give it the beans – the SLK’s exhaust sounds crazier than the Z4’s more noise-police-friendly note.

CURVE COVER

Both cars are classic front-engined, rear-wheel-drive roadsters, and both are independently sprung all-round. The SLK is quite stiffly sprung – the chassis provides plenty of grip and responds well enough to driver input – but if you encounter a broken road surface when there are cornering forces involved, it tends to unsettle the car a bit. With its 18-inch wheels and low profile tyres, the SLK communicates a lot of the road’s surface ruts and bumps into the cabin too. It does improve with speed and it’s much better on the highway. More of a disappointment than the underwhelming but acceptable ride quality is the steering’s general lack of precision and feedback. It’s a little too benign and more feel would have been welcome.

The BMW, on the other hand, is quite the driver’s car. Near-perfect weight distribution, incredible grip and well-contained roll and pitch combine to give it impeccable road manners. The steering is direct, accurate and bristling with feel, the brakes are perfectly weighted, and you just find yourself going harder and harder naturally.

Still, there is a layer of underlying stiffness and some thump and a bit of kick over sharp-edged holes, but our roads are otherwise dealt with pretty well. You are comfortable in the cabin for the most part and ride quality is actually quite good.

Like with most convertibles, there is a fair amount of scuttle shake and you can feel tremors through the body every time you hit a bad patch in both these sport convertibles. But it is more apparent in the Mercedes and its body feels less rigid than the BMW’s.

TOUCH AND FEEL

When it comes to cabin quality, the BMW pips the Merc. The cockpit is snug, with brushed aluminium switches and knobs, and leather on every surface that isn’t metal or a colour screen. Roof up, it is surprisingly roomy and the visibility out is good despite the low seats. However, in hard-top mode, the cabin is cramped and headroom is in short supply. Quality is top-notch and all the controls are intuitively laid out, and the overall mix of space, visibility, simple controls and beautiful finish makes the Z4’s cabin a special place to be.

The same can’t be said about the Merc’s cabin. The all-black cabin looks a bit dull in comparison and it doesn’t have the sophisticated look of the BMW’s interior. The COMAND system too looks outdated compared to the intuitive iDrive system on the Beemer. Overall quality is good though and it leaves you thoroughly convinced of the Mercedes’ premium status. The SLK’s cabin also has slightly more headroom than the Z4 with the roof up, and our test car also came with an optional ‘Vario-roof’, which adds to the cabin ambience. It’s a clear glass panel set into the folding electric roof that turns dark at the touch of a button. It’s a nice but expensive option.

The luggage is likely to be as well accommodated as the occupants in the SLK. With the roof dropped, you retain 225 litres of a 335-litre boot, which looks particularly good next to the BMW Z4’s 180-310 litres.

FINAL CALL

The SLK is a very capable roadster but there is one small problem. It doesn’t have enough to offer the driver like any good roadster should. Sure, it’s got the exhaust note, the roof-down thrills and build quality that’s up there with the best Mercs, but there’s little sensation or sparkle to be found in driving the SLK, and that is hard to forgive in what should be a car that specialises in the feel-good factor.

This is precisely where the BMW Z4 edges the SLK out. It looks special, feels special and the engine is nothing short of fabulous. Then there’s that BMW-ness to its handling — driving a Z4 by the scruff of its neck is a thrilling experience, so it’s got the go to match the show as well. Simply put, the Z4 wins because it is as good at posing outside the Taj as it is at carving up your favourite hill road. And that, we believe, is what a roadster is all about.

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