by Ian Kuah
Painted an eye catching shade of metallic red with a plush cream leather cabin, the sensational Mercedes Vision CLS concept car unveiled at the 2003 Frankfurt International Motor Show caused quite a stir. Apart from debuting the four-door coupe concept, the CLS scored points for Mercedes by promising that this gorgeous car would make it to production largely unaltered. Unsurprisingly, when the production car was shown at New York in 2004, prospective buyers signed up on the spot.
Between 2004 and 2017 the first and second generation CLS sold over 375,000 copies, a big number for a niche market model. Traditionally, the CLS is based on the E-Class platform and uses the same mechanicals apart from a more sporting version of the chassis. However, things have been moving very rapidly at Mercedes in the last few years. With the shift towards greater electrification and the adoption of partial 48V systems first seen in the revised S-class in 2017, the third generation CLS debuts with many new features that the E-Class will only receive when it receives its facelift late next year.
The third generation CLS is a much smoother car to look at than its predecessor, which was incidentally designed at Mercedes' Advanced Design Centre in California. The gen-2 car had a lot more going on visually than the original from 2004, and was perhaps a bit too 'restless' looking for some. This latest car follows Gorden Wagener's sensual purity path, by removing as many lines as possible, relying more on form, proportion and fine detailing for effect. One advantage of this is reduced surface drag, and the new CLS has a class leading drag coefficient of just 0.26.
The timing of the press drive event just before the Geneva Motor Show was such that the new M264 turbocharged four-cylinder gasoline motor that replaces the existing M274 unit had not yet completed its homologation testing. Because of this, while we had 25 six-cylinder gas and diesel test cars available, only two four-cylinder cars were on site. Both wore the optional AMG styling package, but with no model designation, and only those alert enough to realise they were there got to drive them! The four-cylinder gas model will be called the CLS350.
Mercedes started to make reasonably lively four-cylinder gas engines when turbocharging replaced the rather asthmatic supercharged and naturally aspirated motors that had gone before. The latest 2.0-liter inline-four motor is the most efficient Mercedes four yet, and is designed for a specific output upwards of 134 hp/liter, which equates to around 300 hp in the CLS350.. This new engine is part of Mercedes' downsizing and modular engine strategy whereby the new turbocharged 3.0-liter inline-six motor replaces the basic V8 in the E-Class and S-Class models for instance, while the previous mid-range 3.0-liter V6 motors are replaced by the new turbocharged inline-four engine
Where Mercedes' modular engine design was previously centred on V6 and V8 units that shared as many components as possible, the mantra is now centred on these i4 and i6 motors. Importantly, there is no power loss from the downsizing exercise, with the new turbo four showing similar output to the V6 it replaces, while the new turbo i6 has similar punch to the old V8. The second plus point is that both new engines show significant gains in fuel economy at the same time. The M264 engine uses variable timing on the intake camshaft, and a twin scroll turbocharger with a fast acting electric wastegate actuator to optimise both bottom end torque and top-end power.
On the i6 motor the 48V starter-alternator is integrated, while it is belt driven on the i4 engine. Thistechnology enhances step-off by adding a slug of additional electrically derived torque below 2,500 rpm. Apart from these efficiency advantages, the new i4 motor is also smoother and quieter. Specifics such as engine block insulation, quietening technology for the fuel injection hydraulics, and other sound insulation, go a long way towards making up for the loss of two cylinders. The 48V system also takes the sting out of a conventional 12V system when the fuel saving stop-start system is engaged.
Stop-start is much more noticeable on four-cylinder engines, especially diesels, but the high torque and current capability of the 48V system helps the engine restart as seamlessly as the pre-engaged starter on a V12 motor. And if you are in fuel saving mode, the Eco of the stop-start system now cuts the engine even before the car comes to a complete halt. The engine's water pump is electrically driven by the 48V systems, which further reduces fuel sapping mechanical drag. Using this 48V system offers many of the advantages of a hybrid, but without the weight and space penalties of lugging around 300 kg of batteries that encroach on trunk space.
Homologated or not, the new four-cylinder motor does what it says on the tin, and is relatively quiet and vibration free at start up and idle. Like the six-cylinder cars the i4 is mated to Mercedes' 9G-Tronic automatic, which has a paddle shift over-ride as standard. The engine is not six-cylinder quiet on the move, but comes pretty close. Under hard acceleration its voice just makes it to the cabin, and is the unique slightly baritone Mercedes four-cylinder note that distinguishes it from the equivalent Audi and BMW motors. Big pluses are the good performance and snappy throttle response that deliver the promised sporting character under full throttle.
The closeness of the nice forward gear ratios help, but this is clearly an engine that likes life on the edge, and the rev counter needle eagerly flies round the dial when you launch the car from rest and keep the throttle nailed. In Sport mode the transmission keeps everything nice and taut, and will drop two or even three gears if needed, to keep things on the boil. The counterpoint at cruise is that the soundproofing and taller gear ratios make for serene and restful progress, with mechanical noise imperceptible at 80 mph on a light throttle. The acoustic comfort package with double glazed side windows as fitted to all the test cars certainly helps too.
Where the CLS53 AMG rode on air suspension, the four-cylinder test cars were equipped with the middle option of steel springs with adaptive damping. Wearing the optional 19-inch wheels, this car exhibited taut handling and an impressively comfortable ride that frankly was 90% as good as the air suspension. The excellence of the new i4 motor in the CLS no longer makes this the entry-level poverty model. Good performance, sporting response, coupled to impressive refinement are all strong suits of this new engine, whose potential fuel economy in normal driving is indeed something to write home about.
The V6-engined 43, and now the new i6-engined 53 models have been nicknamed "AMG Lite" for the fact that they bring the passion and performance of AMG to a less hardcore package that many people prefer for everyday use. And of course these models are also more affordable. In their time, the 367-hp turbocharged V6 and 4Matic drivetrain made the C43 and E43 AMG my personal favorites for their fine balance of comfortable performance for everyday use, and their own silk ripping V6 soundtrack. Also, until the advent of 4Matic+ in the E63 AMG, the 43 models stood out as cars you could use all year round no matter where you lived.
With the debut of its 53 models, AMG ramps up this concept with its tuned version of the turbocharged and electrified 3.0-liter i6 motor that debuted in the facelifted S-Class last year. Featuring 435 hp at 5,900 rpm, with 383 lb-ft of torque between 1,500 and 5,500 rpm, the M256 i6 motor with EQ Boost starter generator delivers an additional 22 hp and 184 lb-ft under full throttle acceleration. With 4WD traction the CLS53 4Matic+ rockets to 62 mph in just 4.5 seconds, but top speed is electronically limited to 155 mph.
The up and down shift speeds of the AMG Speedshift TCT 9G transmission is as fast and smooth as it gets in a car of this class, and on the demanding twisty mountain roads that made up part of the test route near Barcelona, this car proved quite impressive. Toggling between Sport and Sport+ modes on the Dynamic selector I quickly concluded that Sport+ was too edgy for the road and is best left for the racetrack. Sport mode is just right for fast road use and the great thing is you can combine that setting with the air suspension in Comfort or Sport 1 or Sport 2 modes, and the gearbox in Manual or Sport. Individual mode allows you to then lock these settings in for your different driving moods, or indeed different drivers.
I thought this motor was very punchy and smooth when I drove the S500 last year, but the lower and lighter CLS makes even more of it. The lower Coupe style bodywork and seat position positively encourages you to try harder on a twisty road than you would in the equivalent E-Class. Where the normal 4Matic system has a 45/55 power split on the CLS450, the 4Matic+ system in the AMG car delivers an infinitely variable torque split. I was able to exploit this fully on some of the bends on the mountain route, exiting with power oversteer in the lower gears when there was no other traffic around. The multi-chamber Air Body Control suspension is superb.
Although the AMG version is calibrated more towards performance it still retains impressively comfortable secondary ride around town, coupled with iron-fisted body control and low cornering roll at higher speed in Sport mode. In fact I used Sport as my default mode as the ride. Even on the 8.0J and 9.0J x 19-inch alloys with 245/40ZR19 and 275/35ZR19 tires, it was very comfortable. On that note, as this is a full five-seater I elected to sit in the back for a while to see just how comfortable the rear seat is. The ride was easily as good as the equivalent E-Class, but headroom might be marginal for anyone over 5 ft. 10 in. or so. At 5 ft. 8 in. tall, I was two inches off the headliner.
On the downside, as with many AMG cars, you do hear an exhaust resonance in the back, and the CLS53 is no exception. Some people might enjoy the sound while others might not. Both my test cars came with the basic Burmester audio system. There is a high-end 3D system with additional speakers in the roof and more power, but it costs over 4,900 Euros in Germany. The basic system is around 850 Euros, fantastic value given it produces a clear and focused sound with rich musical tones. It is particularly good on vocals and the texture of individual instruments on well-recorded jazz groups or chamber music comes across particularly well.
The new CLS53 4Matic+ is an exceptional car for its looks, quality and performance, while even the entry-level four-cylinder CLS is a worthy contender. The gap between this third generation CLS and the equivalent E-Class has never felt greater.