Mercedes-Benz SL-Class 2016 Review

Announced in September, the upgraded SL for Australia features a nine-speed automatic transmission and scores optional Active Body Control with curve tilting – not fitted to either car on test. The twin-turbo V8 of the SL 500 is carried over with a slight performance advantage due to the new transmission: 4.3 versus 4.6sec for the 0-100km/h time. More power and torque for the twin-turbo V6 lifts the SL 400's engine output to 270kW and 500Nm.

They come with a powered folding hard-top roof, but the Mercedes SL 400 and SL 500 tested by motoring.com.au during September and October were never likely to be driven any sort of distance with the top lowered.

Not with such cold, wet and blowy weather prevailing throughout south-east Australia at the time.

During a five-minute interlude between gusts, I sat in the SL 500, which was parked in the driveway, and lowered the roof and windows – just to check everything worked to specification – before hurriedly cinching it up watertight once more.

So the week spent assessing the SL 500 was based around its competence as a touring coupe, rather than a roadster. The same was true of the SL 400 a few weeks later. There was no appreciable improvement in weather during the interim.

But on that point, both cars proved to be very well insulated from the elements. Normally you would expect some wind and driveline noise to permeate the gaps between the roof and the body of a convertible – even a hard-top convertible from the three-pointed star.

More than usual, Benz has achieved something highly commendable in dampening noise in the cabin of the SL. Some tyre roar is audible on coarse-chip roads, along with a whisper of wind noise, but the SL – despite the folding roof – is essentially as quiet as an S-Class at cruising speeds.

As for the drivetrains, even measured against cars around the same price or higher, the SL is eerily free of vibration from transmission, prop shaft and driveshafts.

And you'll only hear the rich, mellow, baritone soundtrack of the twin-turbo V8 or the snarling V6 when operating under load, when either engine is winding up for a burst of acceleration. Both are highly responsive engines, although at times the V8's surfeit of power and torque overcame the SL 500's grip in the wet, before being hauled back in by the over-anxious stability control.

The V6 sounds like it works a bit harder. Its pleasing six-cylinder note is present on even light throttle settings, and the nine-speed automatic is calibrated to change up a little later – so the SL 400 always feels ready to pounce. And pounce it does. Give it some serious throttle and it's jumping to 4000rpm and accelerating in a geometric progression from there through to redline.

Coupled to both engines is the new nine-speed automatic transmission, which is very adaptable – changing down precisely when required and complementing the car's braking ahead of a corner. Changes were seamless and swift in both cars.

At 100km/h, the transmission is holding eighth gear, but will shift into ninth with a manual gear change – at which point the engine is revving at just 1300rpm. In Drive the transmission will shift up to ninth at around 110km/h indicated. Gearing was broadly the same for both engines.

That high gearing and the loping, lazy torque of the V8 around town helped the SL 500 achieve an average fuel consumption of 13.5L/100km for the week. For the SL 400, the fuel consumption was markedly better, at 11.8L/100km. On the subject of fuel, the SL 500 had apparently inducted a bad batch, prompting the engine fault warning light to shine for a few days before it cleared itself.

Both cars came with Dynamic Select, the Benz buzz word for a multi-mode system that adjusts dampers, steering assistance, engine mapping and transmission shift points. As well as the Economy, Comfort, Sport and Sport+ modes, there's an individual mode that allows the various outputs to be adjusted independently of each other. With individual mode you can select a softer ride with more aggressive power delivery and sportier steering, or any combination of those parameters.

Steering was reasonably light for the SL 500 in Comfort mode, but the weight loaded up significantly when switched to Sport mode. There was reasonable feedback – particularly in Sport mode – but not the same turn-in as similarly priced sports cars from other prestige brands. The steering was not as direct and the SL 500 felt more like a grand tourer than a sports car.

In contrast, the SL 400 felt lighter in the front end (and through the wheel, even in Sport mode). Even though the V6 variant delivered no more grip than the V8, the SL 400 felt more agile.

The SL 500 provided a respectable level of grip, even in the wet, and the car's handling was reasonably forgiving. In fact, some rivals in the same market sector would be much more of a handful on low-friction surfaces. Unfortunately there was no opportunity to test the SL 500 in the dry, unlike the SL 400.

In the wet the SL 500 would understeer if the braking were left late. But then it would step across into oversteer, which was exacerbated by the application of power – until the stability control took over. Quite simply, the SL 500 was hindered by low adhesion during the week.

But with the entry into the bend sorted beforehand, rolling on the throttle into the bend, the SL 500 adopted a more measured stance. The SL 400 exhibited similar handling traits, but two points became apparent in the dry. One is that the SL has tenacious grip at the rear. It won't break loose on a trailing throttle and accelerating out of a tight hairpin the car's stability and traction control systems work very effectively in combination with the passive dynamics to keep it tracking true.

The second point is also related to that. Because there is so much grip in the rear, the SL is more likely to push out of corners with the power applied. Despite that, the understeer could be reduced by simply lifting the foot off the accelerator.

Ride comfort was quite acceptable even in the hard-core Sport mode, let alone Comfort or Eco modes.

Pre-Safe delivered a variation on the Heimlich manoeuvre as soon as it detected the SL 500 oversteering mid corner, even in Sport mode. The seatbelt would squeeze the occupant hard in the seat and didn't release until it was certain the car wouldn't slide sideways into a tree.

Cruise control held the car precisely to the speed limit on even steep descents, and the car's torquey V8 also maintained speed uphill, but the transmission did drop back a couple of gears on steep grades. Curiously, the smaller-displacement V6 held gears longer uphill, but was equally at home higher in the rev range with the throttle wide open.

Other safety features that were a little over the top at times included the car's autonomous emergency braking system, which would signal a car in front with two loud beeps. But the system wasn't a major distraction the way counterparts can be in some rival cars, and it never overreacted.

On freeways the SL 500 automatically maintained the right position in the lane, but struggled with country roads. After 15 seconds or so, the lane-keep assist system insisted the driver reimpose manual control of the car. Oddly enough, the car's lane-departure warning system informed the driver when the SL 500 was crossing over the line at the side of the road, but the car itself wouldn't steer back into the lane.

On one occasion, when the SL 400's safety system did detect a situation it read as the car crossing a centre line, it braked on one side to steer the car back into the lane fully.

The adaptive headlights incorporated intelligent high-beam assist and were almost foolproof picking out animals without blinding oncoming drivers at night. The system was slow to react in some circumstances, one of those events being a car ahead straightening up on the exit from a bend, but generally I would give the system in both cars a big thumbs-up.

As a package, the SL felt much like a low-riding S-Class. Entering the cabin was easy enough, lowering oneself into the seat, but climbing out was harder – and that's apparently true for other users as well, judging by the scratches left in the scuff plates on the door sills.

The seats were comfortable and supportive, with well designed side bolstering to hold the occupants in place without being too aggressive.

The layout inside the SL was appealing and yet subtle. Approaching either at night as you unlock it, you'll notice the daytime running lights make the transition from blue to white and the light inside the cabin heightens the sense of occasion, shining on the rich leather and the brightwork on the dash.

The instrument binnacle was a busy cluster of readouts that takes some study for information at a glance. That aside however, the driver's position was very flexible for people of different stature.

Unfortunately, the SL's field of vision was obstructed at times by the C pillars behind, although the reversing camera and external mirrors offset that.

The SL 500 was trimmed in black Nappa leather and incorporated the $2750 Night Package, with ambient lighting. The SL 400 featured very attractive Bengal Red leather upholstery and Black Ash high-gloss veneer.

Ergonomically, the both cars featured known Mercedes-Benz conventions, not all of which are entirely logical. The Dynamic Select button was easy enough to find once you knew where it was located, but there's a separate Comfort mode button near the Comand controller that's placed closer to the passenger seat. And the switch for the roof is pulled up to lower the roof, but pressed down to raise it.

Voice recognition coped very well with transcribing an address for the satellite navigation while the car's on the move. It worked very effectively and saved a lot of time entering a new destination for the route.

The boot was large and useful with the roof raised, but with the secondary luggage cover, which can be lowered by a power switch in the boot, there's a considerably reduced volume available for goods and luggage.

Overall, the SL 400 and SL 500 impressed as usefully practical cars for the daily drive, as well as lifting spirits on a weekend jaunt. As is often the case with other Benz models, both will be a keeper for years to come, but I would personally opt for the V6.

2016 Mercedes-Benz SL 400 2016 pricing and specifications:
Price: $221,715 (as tested, plus on-road costs)
Engine: 3.0-litre six-cylinder twin-turbo-petrol
Output: 270kW/500Nm
Transmission: Nine-speed automatic
Fuel: 7.8L/100km (ADR Combined)
CO2: 177g/km (ADR Combined)
Safety Rating: TBA

2016 Mercedes-Benz SL 500 2016 pricing and specifications:
Price: $292,465 (as tested, plus on-road costs)
Engine: 4.7-litre eight-cylinder twin-turbo-petrol
Output: 335kW/700Nm
Transmission: Nine-speed automatic
Fuel: 9.1L/100km (ADR Combined)
CO2: 207g/km (ADR Combined)
Safety Rating: TBA

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