|AMG E53 4MATIC Cabriolet||
3.0-liter Turbo Inline-6 Hybrid
by Ian Kuah
Most people think of open Mercedes in terms of the two-seat SL roadsters that appeared in the mid-1950s. But the history of Mercedes convertibles actually dates back to 1926 when the four-seat Model K derivative of the Type 630 was launched.
After that, the soft-top four-seater was always part of any new Mercedes model range, while the two-seat roadster was a relatively rare beast until the arrival of the 300SL in 1957.
Ironically, it is practicality and a changing marketplace that has witnessed the upswing in four-seat convertible sales and a shrinking demand for premium two-seat roadsters.
The latter saw a huge surge in the late 1980s after a drought of many years. The debut of Mazda's MX5 Miata opened the floodgates, and was followed by the BMW Z4, Mercedes SLK, and Porsche Boxster. The sky seemed to have no limits back then.
In recent years, however, while the little Mazda is now in its fourth generation and is the best selling roadster ever, the market for premium two-seaters has hit the proverbial brick wall. Mercedes is talking about no SLC successor, while SL sales are a fraction of what they once were. Meanwhile, BMW had to axe its pretty 6-Series 2+2 Cabriolet due to poor sales, although the 8 Series Convertible is set to debut next month in LA.
The more practical four-seat convertible seems to be taking the place of these cars with buyers who do not have the luxury of affording or having space for two cars at home.
Mercedes has certainly stepped up to the plate here and currently offers cabriolet versions of their C, E and S-Class ranges with almost the full spread of gasoline and diesel engines available in Europe in the case of the first two.
Enthusiasts are well served by AMG versions of each, the charismatic 4.0-liter bi-turbo V8 C63 AMG formula being available to spice up the smallest of these three convertible ranges, and a more highly tuned version of the same motor powering the S63 AMG Convertible at the other end of the spectrum.
For buyers who want a less edgy but still sporting ride, the C43 AMG Cabriolet, which delivers 3.0-liter bi-turbo V6 power to the tarmac through all four wheels, is a great all-rounder.
If you are wondering why there is no E63 AMG, the hesitancy of Mercedes-AMG to make Coupe and Cabriolet versions of their well-received four-door super sedan stems from the disastrous sales figures of the CLK55 AMG (W208) Coupe and Cabriolet produced the late '90s and its CLK63 AMG (W209) successor of the mid-2000s. But that was then and perhaps they would have more luck today. Nonetheless, once bitten twice shy.
Gorden Wagener's design team has done a great job of increasing the eye appeal of the current Mercedes range, a fact reflected by the strong sales numbers. His philosophy of removing superfluous lines from each design certainly makes for a cleaner look that will better stand the test of time.
The current E-Class Coupe is thus a thing of beauty, and removing the roof of a car with such fine basic proportions makes for an elegant convertible that turns heads at it cruises past.
Fast-Forward to late summer 2018 and we have just left our hotel in downtown Austin, Texas, top down in a gleaming white E53 AMG Cabriolet. It is early on a Sunday morning, and with the warm sun rapidly slicing through any overnight chill hovering around the nearly deserted streets we are heading for the open road.
One thing that has definitely improved since the dawn of the motorcar is creature comforts. I once did the London-to-Brighton Veteran Car Run in a 1982 single-cylinder Benz, and I was tired, aching and frozen after a 40-mile journey that took a good eight hours and included two services and three fuel transfers by the Mercedes Museum mechanic who was my chaperone for the day.
Today, I can have my posterior warmed or cooled according to my mood, while my hair will be kept in place by the power operated Aircap device that rises from the top of the front windscreen frame and the wind deflector that emerges from between the rear seat headrests. Front seat occupants can even have warm air directed at their necks by the Airscarf duct built into the headrests.
And with state-of-the-art sat-nav guiding us either via the big screen or a simplified version on the instrument pack or even Head-Up Display, we should never get lost.
The punch and refinement of the 3.0-liter turbocharged motor is matched by the sheer sophistication of the rest of the car. The fit and finish of the body panels is as good as it gets in this segment, and the interior with its two-tone leather trim and stitched leather on the dashboard looks and feels suitably classy.
When you're in the front seats and facing forwards with the three-layer ragtop in place, there is no difference between this car and the Coupe in the view forwards and refinement.
Rear seat room is fine for people under 5 ft. 10 in, as is headroom. Perhaps the greatest irony is that width apart, the rear seat room is marginally superior to that of the larger and more expensive S-Class Cabriolet.
You can choose from several kinds of wood trim, but apart from its susceptibility to fingerprints we liked the black piano wood fitted to the test car, where the dashboard and door trim panels have yacht-like inlays to add more visual interest.
The optional Burmester high-end audio system fitted to our test car plays music with superior tonal balance and realism than competing systems used by other car marques. Since the sound escapes into the environment with the top down the cabin acoustic is very different from the Coupe, but Burmester has a unique algorithm that compensates for this as best as possible.
The one area all such cars run into a compromise is in trunk space. Because the ragtop has to fold into its compartment behind the rear seat, the luggage compartment height is restricted when the roof is in the down position. This means some clever packing with modestly sized bags if a long trip is on the cards.
While all these gadgets are available on any E-Class Convertible, even the lowly four-cylinder models sold in Europe and Asia, what makes our test car exciting is the technology that underpins the E53 AMG badges on its trunk lid.
Power comes from the new bi-turbo straight-six motor introduced in the facelifted S-Class last year. It also means that power is dispensed through 4Matic+, the AMG fettled variant of the Mercedes 4Matic all-wheel-drive system.
This straight-six (M256) 3.0-liter motor is part of the latest Mercedes modular engine family that encompasses the 2.0-liter inline four (M264) and 4.0-liter V8 (M176) motors. These 2.0, 3.0 and 4.0-liter engines all share a common 83.0 x 92.0mm bore stroke for an individual cylinder capacity of 500 cc.
Mercedes chose this straight-six engine as their first ever power unit to be mated with a starter/generator feeding a partial 48-volt electrical system that delivers a torque boost to improve low-end response and punch.
At its debut last year, Mercedes billed this new six-cylinder motor powerful enough to replace the V8 from the previous generation S-Class. With this six taking on the mantle of the previous generation V8 in the S500 the new 4.0-liter bi-turbo V8 engine now justifies the S560 designation.
The smooth and potent six delivers 435 hp at 5,900rpm and 384 lb-ft of torque between 1,500 and 5,500 rpm, with peak torque boosted by an additional 184 lb-ft from the beltless starter generator for short periods.
The additional structural reinforcement built into its shell means this 4WD Cabriolet tips the scales at a whopping 4,530 lb, some 100 lb heavier than the latest S500 limo! However, thanks to the peerless traction of the 4Matic+ all-wheel-drive the stopwatch records an impressively rapid 0-62 mph sprint of 4.5 seconds, while top speed is electronically limited to 155 mph. So how did the engineers extract so much reliable power from a mere 3.0 liter six?
"We knew we would need a big turbocharger to get the top-end power," says powertrain development engineer, Kay Dietzel. "Thanks to the partial 48-volt electrical system, we are able to use the starter/generator to provide an additional 184 lb-ft of torque when you step on the gas at low revs, with the first stage electrically driven turbocharger spinning up to boost the low-end torque," he explained.
"By this time the exhaust gas driven turbocharger has spun up and is boosting hard to provide the strong mid and top end power. The real trick was to make these three stages work together perfectly."
Their seamless application results in excellent low-speed throttle response, eagerness to rev, and a strong and progressive flow of power, while the crisp straight-six soundtrack becomes more visceral at high revs, especially when you are driving al fresco. And with the exhaust flaps wide open as you pass high walls or drive through a tunnel this can even reach spine-tingling levels.
The counterpoint is that a good inline-6 engine is inherently balanced where a V6 requires a balance weight on the end of its crankshaft. The extra silkiness of the new engine is both palpable and quietly satisfying.
With the active damping system adjustable at the touch of the rocker switch on the console, we were able to instantly adapt the suspension to the road conditions. The Comfort setting works nicely around town and helps to take the edge off the firmer ride of the optional 20-inch alloys fitted in place of the 19s on our test car.
Sport is a nice compromise when you get onto faster roads with bends. That said because this was Texas rather than California we never found any challenging bends on our test route, so a proper verdict on handling will have to wait for another time. Suffice to say that while the E53 AMG Cabriolet felt responsive and agile despite its weight, it is best described as a refined cruiser with a sporting edge. In that respect, it does what it says on the tin.
Some enthusiasts have called these sporty six-cylinder models "AMG Lite" but the fact is that they provide the perfect halfway house between mainstream Mercedes models and the hardcore AMG V8 genre with their rousing NASCAR grade soundtrack.
The good sales figures have proven that for many customers "AMG Lite" with its standard 4WD is the ideal formula, especially for those who live in a part of the country where it rains a lot or snows in winter. And with its snug three-layer top up or down, the E53 AMG 4Matic+ Cabriolet is a car you really can use and enjoy 365 days of the year.