BMW 3 Series vs Mercedes-Benz SL-Class

What's the difference?

I thoroughly enjoyed my time in the BMW 320i M Sport. It’s fun to drive and I felt connected to what the car was doing on the road. The harder ride may not appeal to some but I didn’t mind it. The cosy back seat and boot mean it will probably suit a smaller family best and one which doesn’t have to worry about carrying a lot of gear around regularly, but it suited my needs just fine.

I reckon this is a car for those drivers who don’t want to compromise on performance but still have a kid or two. If you’re after the cushioned comfort of a Merc, this won’t appeal but I didn't want to give this one back and happily give it a firm 8/10.

My son liked the sports car looks and enjoyed the amenities in his row. He gives it a 10/10.

The SL's overall score is somewhat skewed by everyday concerns, and rules are rules - an average punter will find the price of this car somewhat confusing and the devil-may-care attitude to fuel consumption bewildering.

If neither of these things are a problem, then the SL63 makes plenty of - well, not sense, because it's not a particularly clever or considered car - but it fills a niche that not so long ago we all thought would go the way of the dodo.

The fact it sells so few examples is betrayed by some of the cabin amenities and the fact that Mercedes hasn't put much effort into reducing the car's weight to improve its consumption or sharpen up the handling.

The fact it still exists at all is pretty damn cool, though, and for certain people an SL63 purchase is the culmination of a lot of hard work.

If it is your dream car, the SL63 won't disappoint. Everyone who rode with me said it was mightily impressive, but you've got to really want it. When you're not far off buying a Ferrari California T or Aston Martin V12 Vantage S for the money, you'll need a real yearning for the three-pointed star to go this way. And if you do, good luck to you - you've probably worked quite hard to get here.

Sharper than its predecessor, the new 320i has LED everything with the rear lights being longer and curving around to the sides of the car.

The classic 'kidney' grille is darkened and more pronounced, with the black panelling extending to the rear to create an unapologetically sporty presence. A presence that’s accentuated by the twin exhausts.

The batcave interior with its black headliner, black seats… black everything, looks smart and stylish.

You do have a fair bit of harder touchpoints throughout but the customisable ambient lighting helps to soften the overall effect.

With its 2068mm width, 4709mm length and 1435mm height, the sedan makes its presence known without feeling cumbersome to manoeuvre. Urban dwellers need not fear their local car park!

The SL has always been completely unapologetic about its size and seems to be designed to accentuate rather than hide its length and width. The long bonnet screams power and prestige, and get out of my way, and is reminiscent of the little-loved McLaren SLR project of some years ago.

The size of the Mercedes logo on the huge front grille leaves you in little doubt about the brand of car that’s about to pass you at speed and some might say (okay, I would) that its large surface area is a little vulgar.

Like the SLR, the design doesn't seem to have a particularly cohesive strategy, with a number of Mercedes elements from around the traps that climb over each other. Roof up it looks awkward because of the gigantic posterior while with the roof down it looks overly long and, again, tail-heavy.

Folding hardtops are notoriously cumbersome and need a lot of room to hide them, but the silent operation is something to behold.

Elements that are worth deleting if possible are the dodgy 'Biturbo' badges. It's that kind of bling that gets people raising their little finger at you.

For such a sleek looking sedan, it’s generous up front with plenty of head and legroom.

You can adjust the seat to sit quite low and both front seats have extendable under-thigh supports, which should excite taller drivers. 

My 189cm (6’2”) brother has the 328i and is very comfortable but taller front passengers will encroach on back seat passenger comfort.

The front seats are quite firm on the backside, they also lack adjustable lumbar support, so expect to stretch the kinks out on a longer trip.

The amenities and tech feel well thought out and easy enough to use. The 12.3-inch touchscreen multimedia system looks great and has the best-looking graphics I’ve sampled.

The BMW system is intuitive to use once you get used to it. If you’re not interested in using the touchscreen, you can also utilise the rotary-wheel for menu selections.

There’s also Bluetooth connectivity, wireless Apple CarPlay and Android Auto plus built-in satellite navigation.

The 12.3-inch digital instrument panel is customisable and the information displayed simply but you won’t really look at it because of the head-up display.

Front occupants enjoy a wireless charging pad for their smart phone, a USB-A and USB-C port plus a 12-volt socket. Rear passengers get a couple of USB-C ports, too.

The storage is good for this size sedan but overall passenger room takes priority, but the glove box and middle console will suffice for everyday use.

While it may not excite others, I love the big bottle holders in the doors. They’re large enough for my big 1.5L bottle and angled for easy access. These are found in the rear doors as well.

Back seat passengers enjoy climate control, directional air vents, two cupholders, netted map pockets and reading lights.

My six-year old was happy with the amenities and lower ground clearance because he felt comfortable and had his independence.

The boot offers a good capacity of 480L and the aperture isn’t too narrow, so you can comfortably access items if they roll to the back.

I had plenty of room for my little family’s needs but if you’re a larger family, you may need to get strategic with gear storage.

Being a base model, you do miss out on a powered tailgate, which is a shame but not too much of an issue given this is a sedan and the lid isn’t heavy.

There’s also no spare tyre or even a puncture repair kit but you have run-flats, so you should be able to limp to a service centre if need be.

“Practicality” is about as relevant to this car as a code of ethics is to a drug dealer or a contract killer, because the SL63 buyer is hardly worried about cupholders and boot space. For what it's worth, there are four cupholders in the two-seater cabin (which might explain why owners aren't worried about their liquid carrying prospects) and a minimum boot space of 364 litres and a maximum - with roof up - of 504, which is actually not bad.

Cleverly, there's a little robot-operated luggage cover inside the deep boot that stops your gear from being crushed when the roof goes down.

There's also space in the long doors where you might secrete a bottle of wine that would get a NSW Premier fired if he thanks you for it, and a bin in the console to hide your phone.

It’s difficult to ponder the idea of value when a car is already approaching $400,000 at a rapid rate even before you start piling on the options. On the plus side, for a list price of $368,715 you do get an extremely long list of standard equipment.

The SL has always been completely unapologetic about its size.

Edited highlights include leather on almost every available surface, heated and cooled electric seats with a fan heater for your neck, a B&O stereo that will shatter the windscreen on request, aluminium trim that's real aluminium (mostly), Active Ride suspension, sat nav, dual-zone climate control, active cruise, LED headlights and a huge swag of safety gear.

The 12-speaker stereo also has DVD, limited smartphone integration via Mercedes' COMAND system, a seven-inch screen and, of course, Bluetooth.

The 320i M Sport has the ‘baby’ engine in the 3 Series line-up but the 2.0-litre, four-cylinder turbo-petrol powertrain still delivers on power with a maximum output of 135kW/300Nm. 

This is a rear-wheel drive and has an eight-speed auto-transmission which delivers very smooth gear changes.

Despite having the smaller engine, it can still go from 0-100km/h in just 7.4 seconds.

The SL63 is powered by Mercedes’ increasingly famous V8, with two turbos along for the ride to add oomph and cut the car's famous consumption, at least slightly. The 5.5-litre unit produces a massive 430kW and a scarcely believable 900Nm of torque.

All of that heads rearward via a seven-speed dual-clutch transmission that helps sling the 4.6m, 1848kg machine to 100km/h in 4.1 seconds.

In a world with rising fuel prices, the efficiency of this decently powered sedan should excite you.

The official combined fuel cycle is 6.5L/100km. Real world testing saw my figure at 7.4L/100km after a mix of open-road and urban driving this week.

I thought that was great for how hard I drove it and for the power, you won’t be wincing when you put your foot down. I would expect it to be higher in an urban setting.

The 320i has a 59L fuel tank and based on the official combined cycle figure, you should get just over 900km of driving range, which is great, especially if you do 'roadies' like me!

Much as is the case with the price, there's no real way to soften the blow here - the SL63 drinks like a footballer on Mad Monday, except it does it every day. The official combined cycle figure of 10.2L/100km is quite easy to double, as we did, averaging 21L/100km in mostly flowing suburban traffic. In the car’s defence, the accelerator pedal spent a good deal of time near the firewall.

The SL does have stop-start to help reduce its considerable environmental impact.

There's a lot that I like about how this performs but a highlight is how eagerly the car responds when you accelerate.

However, it’s not unbridled power. There’s no bucking at the front or shuddering through the steering wheel. It’s controlled but still very fun.

The lower centre of gravity and coupe-like height of this does mean it handles corners well and the bolstered seats hold you firmly into place, meaning you can be free to drive this a little harder than you might normally. Which I did and can confirm it handles itself well.

This has the M Sport suspension, which means it’s stiff, but you feel very connected to the road.

You do get a lot of talk-back from bumps in the road but unless you hit a big pothole, you never feel rattled by them.

But it is a harder ride than other luxury models, which doesn’t bother me as I like the handling, but if you want limo-like comfort, look elsewhere.

The cabin is very nice to spend a lot of time in and relatively quiet, even at higher speeds.

The 11.4m turning circle and sleek dimensions makes it very handy to park, even in tight car parks. The nose is long but the front and rear parking sensors take out any ‘will I make it’ moments and the super clear reversing camera is great. 

There are a number of impressive things about the way the SL drives. Firstly, astronauts will be familiar with the galactic thrust of the V8. It seems endless, seamless and ready to sling the big coupe into the outer atmosphere. Few engines of any kind can match the relentless go on offer in the SL and much of the credit should go to the seven-speed twin-clutch transmission.

When you jump on the brakes and shift down, the exhaust keeps the show going with angry crackles and pops.

Containing a torque figure like the twin-turbo V8's requires a lot of electro-trickery to stop you from being launched off the road. The great thing about all that stuff is that it works unobtrusively and smoothly.

Mashing the carpet in an SL without traction control would create much sound and smoke but little forward progress, such is the twist on tap. The SL has a range of modes from full-nanny (which is meant to keep you on the slippery Alpine road you've chosen to get you to some Swiss ski resort) while turning the dial all the way around to Race loosens the bonds.

It's in this mode you'll have the most fun and it does seem that the intermediate settings are a bit of a waste of time. Race mode does little to diminish the amazing ride quality provided by the active suspension setup, but relaxes the reins on the huge rear tyres. Exiting roundabouts is suddenly a huge laugh, with the tail cheerfully breaking traction and the two-mode exhaust thundering in a most pleasant way.

Better still is that when you jump on the brakes and shift down, the exhaust keeps the show going with angry crackles and pops, with more on the way when you lift off. There's little to match the aural pleasures of a properly tuned V8 and Mercedes has resisted the temptation to quieten it down on the outside and generate a fake noise for the inside. Although that would be stupid in a convertible, if you think about it.

The SL63, despite its AMG badge, isn't about all-out handling, of course. The Ferrari California would definitely show it how it’s done on a winding country road. The SL is more about flow, building momentum and rarely shifting down to second gear. The monstrous torque is enough to keep things rolling but should you wish for a bit more of the exhaust bellow, second is there for the taking.

Hustling the big convertible feels wrong, not because it can't do it, but because it's not really what it's for. Having said that, it offers a kind of fun that nothing else on Earth will provide, not even a Bentley GTC.

With the roof up, the SL63 is a quiet place but not remarkably so. The huge sticky tyres do the cabin's hush no favours, with an annoying roar on a wider range of surfaces than you might expect.

Roof down, it's hardly a paragon of virtue. A lot of wind noise reaches the cabin, even well below the huge speeds the SL can reach. So if you want to talk, it's windows up you'll need to deploy the mesh screen that bridges the roll hoops.

Six airbags, ABS, stability and traction controls, blind-spot sensor, lane-departure warning, brake assist, active safety bonnet, lane-keep assist, driver attention detection, AEB.

The 320i comes with a five-year/unlimited km warranty, which is standard for this class.

You can choose between a three- or five-year capped-priced servicing plan. The five-year plan costs just $2150, or $430 a year, which is competitive for this class.

Like other BMWs, servicing intervals are condition-based, with the car letting you know when it needs to be serviced.

The SL63 is covered by Mercedes' three-year/unlimited kilometre warranty. And, er, that's it.