Review: Mercedes X166 GL 63 AMG (2013-15)

Overview

Released in Australia in May 2013, the Mercedes-Benz X166 GL 63 AMG was a four-wheel drive wagon with seven seats. Manufactured in Tuscaloosa, USA, the Mercedes X166 GL 63 AMG was powered by a 5.5-litre biturbo V8 petrol engine that was mated to a seven-speed automatic transmission.

M157 biturbo V8 engine

The M157 V8 engine had an aluminium block with cast-in aluminium-silicon (Silitec) cylinder liners, forged crankshaft made of 38MnS6BY steel alloy (a combination of manganese, sulphur, boron and yttrium) with eight counterweights and rotating in five main bearings, fracture-split forged connecting rods, an aluminium cylinder head, double overhead camshafts (driven by three high-performance chains), variable intake and exhaust camshaft adjustment over a range of 40 degrees via four pivoting actuators, four valves per cylinder and a compression ratio of 10.0:1. Furthermore, the M 157 had a dry weight of 204 kg, maximum engine speed of 6400 rpm and Bosch MED 17.7.3 control unit.

Significantly, the M157 engine had spray-guided direct injection with piezo fuel injectors (operating at 100 to 200 bar on a demand-related basis), a Garrett MGT2260MSL turbocharger for each cylinder bank (welded to the exhaust manifold) and air/water intercooling. For greater efficiency, the M157 engine had an ‘ECO start/stop system’ – which the driver could disable if desired – and multi-spark ignition whereby the spark plugs could fire multiple times during the combustion sequence for more efficient combustion.

The Mercedes X166 GL 63 AMG could accelerate from rest to 100 km/h in 4.9 seconds and had an electronically-limited top speed of 250 km/h. Over the combined ADR 81/02 test cycle, fuel consumption was 12.3 litres per 100 km.

AMG Speedshift Plus 7G-Tronic

The seven-speed AMG Speedshift Plus 7G-Tronic transmission enabled the driver to select from three modes:

• ‘Controlled Efficiency’, ‘C’, for softer throttle response, smooth gearshifts, acceleration from rest in second gear (generally), early upshifts and activation of the ECO start/stop to reduce fuel consumption;
• ‘Sport’, ‘S’, for greater throttle response, gear changes at higher engine speeds, faster gearshifts, disabled the ECO start/stop function, activated a double declutching function when downshifting and, for faster gearshifts under full loads, enabled the engine to partially suppress ignition and injection in individual cylinders; and,
• ‘Manual’, ‘M’, for gear shifting solely via the steering wheel gearshift paddles.

Gear ratios for the AMG Speedshift Plus 7G-Tronic were 4.38 (1st), 2.86 (2nd), 1.92 (3rd), 1.37 (4th), 1.00 (5th), 0.82 (6th) and 0.73 (7th); the final drive ratio was 3.47.

Dimensions

Compared to the X166 GL 500 , the X166 GL 63 AMG was 26 mm longer (at 5146 mm) and 64 mm wider (1998 mm), but was the same height (1850 mm) and had the same length wheelbase (3075 mm); kerb weight, however, increased by 135 kg to 2580 kg.

Maximum braked towing capacity for the GL 63 AMG was 3250 kg.

Suspension: Airmatic, Adaptive Damping System and Active Curve System

TThe GL 63 AMG had double wishbone front suspension and independent, multi-link rear suspension. Like the X166 GL 350 BlueTec and GL 500 , the GL 63 AMG was fitted with Mercedes-Benz’s ‘Airmatic’ air suspension with Adaptive Damping System (ADS) which consisted of:

• Air-filled spring struts on the front axle with integral ADS dampers;
• Air springs with separate ADS dampers on the rear axle;
• Electric compressor with central pressure reservoir and pressure sensor;
• Air spring valves;
• Sensors for level control and damping control; and,
• An electronic control unit.

For GL 63 AMG, changes included AMG-specific air spring struts, AMG-specific elastokinematics for the front axle and a more robust stabiliser bar for the rear axle.

Airmatic air suspension could compensate for variations in vehicle load and driving state, while also acting as a level control system. For speeds above 70 km/h or when the ‘Sport plus’ mode was engaged, the air suspension would lower the body by 10 mm to reduce drag and increase stability. For off-road use, the air springs could increase ground clearance by up to 60 mm.

ADS was a fully automatic, electronically-controlled system which adapted the damping force at each wheel according to the road and driver behavior to reduce the forces exerted on the body by the movement of the wheels; the driver could also select from ‘Comfort’, ‘Sport’ and ‘Sport plus’ modes. ADS had four maps which it could use based on steering angle, turning angle sensors, vehicle speed and braking application:

• Level 1: soft rebound and soft compression for comfortable ride characteristics, suitable for little longitudinal and lateral acceleration;
• Level 2: soft rebound and firm compression (skyhook mode);
• Level 3: firm rebound and soft compression (skyhook mode); and,
• Level 4: firm rebound and firm compression, for minimising wheel load fluctuations when cornering and braking for more secure handling.

While Level 1 would be used for low levels of body movement, greater movement would result in the skyhook algorithm alternating between Levels 2 and 3 – by activating the fast-acting solenoid valves – to counter body roll and pitch. In more ‘dynamic’ handling conditions or when the ‘Sport’ or ‘Sport plus’ suspension modes were engaged, Level 4 would be used.

Also fitted as standard, the Active Curve System used active anti-roll bars on the front and rear axles to control body roll according to lateral acceleration, road speed and the suspension mode selected. When driving straight ahead, rotary actuators would decouple the two halves of the front and rear anti-roll bars so that they were not active. When the active anti-roll bars were operating,

• A hydraulic pump would feed oil to the anti-roll bar circuits;
• The active anti-roll bars had internal hydraulic rotary actuators with six-oil filled chambers, three of which were pressured for each direction of travel (i.e. cornering left or right). Furthermore, the front valve block had the task of distributing the oil flow between the front and rear axles, regardless of load; and,
• Pressure control valves and directional control valves that were integrated into the valve blocks at the front and rear axles would set the desired pressure and twist the active anti-roll bars in the appropriate direction.

Steering

The Mercedes GL 63 AMG had electromechanical, rack-and-pinion steering. The level of power assistance varied with vehicle speed and the suspension mode selected.

4MATIC four-wheel drive

The Mercedes X166 GL 63 AMG had a full-time four-wheel drive system (‘4MATIC’) with open differentials. In normal conditions, the 4MATIC system provided a 40:60 front:rear torque split. In the event that any wheel lost traction, the four-wheel traction control system (‘4ETS’) would brake that spinning wheel so that torque would be transferred to the wheels with grip.

Features of the 4MATIC system included:

• Downhill Speed Regulation (DSR): designed for steep downhill gradients and activated by pushing a button in the centre console. With DSR, vehicle speed would be kept constant by engine and transmission control, and automatic braking. While the system would initially set a speed of 6 km/h, the driver could use the cruise control stalk to set the desired downhill speed between 4 km/h (minimum) and 18 km/h (maximum); and,
• Start-Off Assist: helped the vehicle more safely accelerate from rest when on steep uphill gradients, by preventing the vehicle from rolling bac kWards as the driver moved their foot from the brake pedal to the accelerator. During this period, brake pressure would be provided by an ‘actively controllable’ brake servo unit. Start-Off Assist was automatically activated by an inclination sensor.

Safety equipment

Standard safety equipment for the Mercedes GL 63 AMG included dual front airbags (two-stage), a driver’s knee airbag, front side airbags (combined thorax/pelvis airbag), full-length curtain airbags (i.e. for all three rows of seats), ABS, electronic brake force distribution, brake assist, electronic stability control, traction control, front seatbelt pre-tensioners and load limiting seatbelts for the front and outer second row passengers.

As standard, the X166 GL 63 AMG was also fitted with:

• Pre-Safe: in the event that an accident was anticipated, Pre-Safe would prepare the vehicle by tensioning the front seat belts, inflating the air cushions in the multicontour seats and closing the sunroof and windows (if open);
• Distronic Plus (adaptive cruise control with brake warning): an ‘adaptive’ cruise control system which used two short-range radar sensors positioned behind the front bumper to monitor the road up to 30 metres ahead, and a long-range radar located behind the radiator grille which had a range of 200 metres. Operating at speeds up to 200 km/h, Distronic Plus used an electronic control unit to analyse the information from both radar systems to calculate the engine, automatic transmission and braking parameters required for proximity control. As such, Distronic Plus could automatically apply the brakes to prevent the vehicle from becoming too close to traffic ahead (the time interval could be specified) and accelerate back to the set speed when traffic allowed. To accelerate from rest, the driver only needed to operate the Distronic stalk on the steering column or briefly depress the accelerator pedal. With Distronic Plus, automatic deceleration of up to four (4) m/s²was possible. If Distronic Plus detected that heavier braking was required, a warning light would illuminate in the instrument cluster and be accompanied by an audible warning. Furthermore, the electronic proximity control system could be activated independently of Distronic Plus at speeds over 30 km/h to alert the driver if they were approaching another vehicle too rapidly;
• Brake Assist Plus: used a 24 GHz radar sensor with a range of 30 metres and a 77 GHz radar sensor with a range of 200 metres to monitor the distance to the vehicle ahead and would warn the driver if there was a risk of a collision. Brake Assist Plus could detect vehicles when travelling at speeds up to 200 km/h, and stationary objects when the driver was travelling at 7 km/h to 72 km/h. Significantly, Brake Assist Plus could calculate the necessary brake force assistance to prevent a rear-end collision, build up that pressure in the braking system and provide it as soon as the brake pedal was depressed for ‘the best possible deceleration’;
• Pre-Safe Brake (autonomous emergency braking): using two 24 GHz sensors behind the front bumper which had a range of 30 metres and a 77 GHz radar which had a range of 150 metres, Pre-Safe Brake operated at speeds between 30 km/h and 200 km/h, and at speeds below 70 km/h if the vehicle was approaching a stationary queue of traffic. Around 2.6 seconds before the anticipated moment of impact, an audible warning would sound and a red warning would appear in the tachometer. Around 1.6 before the calculated impact, the first stage of Pre-Safe Brake would initiate partial braking autonomously with around 40 per cent of the maximum braking power (approximately four (4) m/s²); the Pre-Safe occupant protections system would also be activated. If the driver then applied the brakes, maximum braking force would be made available. If the driver failed to react, Pre-Safe Brake would – in its second stage – initiate autonomous emergency braking (i.e. maximum braking power) around 0.6 seconds before the unavoidable collision to reduce the severity of the impact;
• Active Lane Keeping Assist: could detect when the adjacent lane was occupied (including oncoming traffic) and prevent the driver from inadvertently exiting from the lane when it was not safe to do so by applying a corrective braking force to the wheels on one side of the vehicle;
• Active Blind Spot Assistance: active at speeds above 60 km/h, a corrective braking force would be applied to the wheels on one side of the vehicle if the driver attempted to change lanes when a vehicle was detected in the driver’s blind spot; and,
• Attention Assist: operated at speeds in excess of 80 km/h and monitored driver behaviour and steering movements for signs of drowsiness; if detected, the driver would be provided with visual and audible warnings.

Brakes: GL 63 AMG

Like the W166 ML 63 AMG , the GL 63 AMG had 390 mm by 36 mm front brake discs with six-piston callipers and 345 mm by 26 mm rear discs with single-piston floating callipers; both front and rear discs were ventilated and perforated.

Features: Mercedes GL 63 AMG

Standard features for the Mercedes GL 63 AMG included 21-inch five-spoke AMG alloy wheels with 295/40 R21 tyres, a Harman Kardon Logic7 surround sound system with a digital radio tuner (DAB+), CD/DVD player, MP3/WMA/AAC compatibility, 10GB music storage and auxiliary inputs (USB/iPod/memory card), COMAND APS with a 17.8 cm display, HDD satellite navigation, digital TV tuner (DVB), Bluetooth connectivity and voice recognition (‘Linguatronic’), multi-contour AMG front seats with designo leather centre panels, power adjustable and ventilated front seats, heated front and rear seats, four-zone climate control air conditioning (‘Thermotronic’), cruise control with speed limiter (‘Speedtronic’), directional bi-xenon headlights with washers, daytime LED running lights, automatic headlights, rain-sensing wipers, front and rear parking sensors, four cameras for 360 degree surround views, 40/60 split and folding second row seats, power folding second row seats for access to the third row seats (‘Easy-Entry’), nappa leather AMG steering wheel, remote central locking, keyless entry and start (‘keyless go’), power adjustable mirrors with heating and folding functions, power windows, a power adjustable steering column (for height and reach), a powered-operated glass sunroof, power-operated tailgate, electric parking brake, 12 volt power outlets, ambient lighting, black ‘Dinamica’ microfibre roof lining, roof rails, tinted windows, rear privacy glass, cargo cover and net, TFT instrument cluster, ‘designo’ velour floor mats, illuminated side sills, dark graphite poplar wood trim, tyre pressure monitoring, a trip computer, an alarm and an immobiliser.

The Mercedes X166 GL 63 AMG also featured ‘Active Parking Assist’ which used sensors on the front bumper to measure parking spaces and provided automated steering for the parking manoeuvre.

May 2015 update

From May 2015, the Mercedes GL 63 AMG was specified with the ‘AMG Driver’s Package’ which increased the vehicle’s top speed to 270 km/h.

Brochure

• Brochure: Mercedes-Benz X166 GL-Class (October 2012)

Related links

• Press Kit: Mercedes-Benz X166 GL-Class (July 2012)
• Specifications: Mercedes-Benz X166 GL-Class (July 2014)
• Wikipedia.org: Mercedes-Benz X166 GL-Class