Mercedes-Benz previews new GLA compact SUV; fuel economy as high as 54.7 mpg in diesel version

2015 GLA-Class. Click to enlarge.

Mercedes-Benz previewed the new 2015 GLA-Class compact SUV prior to its global debut at the International Motor Show (IAA) in Frankfurt next month. The GLA, which will go on sale in 2014, is Mercedes-Benz’ first entry into the fast-growing compact SUV segment. It is also the first Mercedes-Benz SUV to be optionally available with the new-generation permanent all-wheel drive system 4MATIC, with fully variable torque distribution. ECO stop/start is standard.

Initially the power range of the 1.6 and 2.0-liter gasoline engines will extend from 115 kW (156 hp) in the GLA 200 to 155 kW (211 hp) in the GLA 250. The GLA will also offer two 2.2-liter diesel variants. The GLA 200 CDI develops 100 kW (136 hp) and maximum torque of 300 N·m (221 lb-ft), with fuel consumption of 4.3 l/100 km (54.7 mpg_US) and 114 g CO₂ per kilometer (provisional figure). The GLA 220 CDI develops 125 kW (170 hp) and 350 N·m (258 lb-ft).

The GLA 250 4MATIC accelerates from zero to 100 km/h in 7.1 seconds, with a top speed of 235 km/h and a combined fuel consumption figure of 7.1 liters of gasoline per 100 km (33 mpg_US) and 151 g CO₂/km—all provisional figures.

Mercedes-Benz, SUVs and compacts
The new GLA brings the SUV portfolio of Mercedes-Benz to 5 model series (GLA, GLK, ML, GL and G)—the widest range of any European premium manufacturer.
The GLA is also the fourth of a total of five new compact models from Mercedes-Benz—a segment in which the company is experiencing strong sales.
In the first half of 2013, for example, 173,362 units of the A and B‑Class and the new CLA Coupé were delivered worldwide (+58.0%). The new A-Class has a very high conquest rate: around 50% of the buyers in Europe come from other brands.

The GLA 200 CDI engine has been reengineered for greater efficiency. The modifications include optimization of the belt drive, a cylinder head package with different roller bearings and additional finishing, optimization of the vacuum pump, aluminium pistons with optimized assembly clearances and a low-friction ring package, the roller bearings of the Lanchester balancer shaft and pressure sensor combustion control in the cylinder head.

The engines are combined with a six-speed manual transmission or with the 7G-DCT dual clutch automatic transmission (standard for GLA 250, GLA 220 CDI and the 4MATIC models)

Aerodynamics. The GLA has a segment-leading Cd figure of 0.29. At 0.66 m² the frontal area Cd x A, which decisively affects fuel consumption from around 60 km/h, is likewise a top figure.

The good air flow characteristics, which are a major contributory factor to the vehicle’s low fuel consumption in everyday conditions, result from numerous aerodynamic optimization measures. These include a low A-pillar step with suitable A-pillar geometry and aerodynamically optimized exterior mirror housings.

The rear end is also streamlined. The measures here include the roof spoiler lip and the aerodynamically shaped tail lights. Rear spoilers at the sides ensure that the airflow breaks off for optimal aerodynamic efficiency. Seals in the front bumper (radiator area incl. around the headlamps) and radiator shutters for regulation of the cooling air as required round off the aerodynamic measures.

Extensive underbody panelling, additional panelling in the middle area of the rear axle and an aerodynamically optimized rear silencer followed by a diffuser improve the flow of air beneath the underbody.

Numerous measures have also been taken to reduce wind noise in the GLA. These e.g. include a multi-level door sealing concept, additional sealing of the joint between the tailgate and the roof and side seals on the tailgate. Particularly rigid window frames prevent the airflow from pulling on the doors at higher speeds, and reduce vibrations. External noise has also been minimized by the low A-pillar step and exterior mirrors connected to the body by a stem.

Chassis. The chassis of the GLA features a McPherson front axle and an independent multilink rear suspension. Three control arms and one trailing arm per wheel manage the incoming forces—longitudinal and lateral dynamics are independent of one another. The wheel carriers and spring control arms are of aluminium to reduce the unsprung masses. In the versions with 4MATIC, the rear axle carrier is isolated with rubber bushings for the benefit of ride comfort.

Compared to conventional systems, the electromechanical power steering provides better feedback to the driver and contributes to the vehicle’s overall efficiency, as the servo assistance only requires energy when the vehicle is actually steered. It also allows various steering assistance functions that are initiated by the ESP control unit.

These include countersteering when the vehicle oversteers, steering corrections when braking on surfaces with different levels of grip, reducing the effects of front-wheel drive on the steering and compensation of cross-winds and road camber.

The GLA has an extremely rigid body, and therefore the basis for stable and safe handling characteristics both on and off the road, as well as a high level of NVH comfort. There are additional reinforcements e.g. to the B-pillars, front damper domes, side members and underbody.

4MATIC. The components of the 4MATIC system include the power take-off to the rear axle that is integrated into the 7G-DCT automatic dual clutch transmission, and the rear-axle gear with integrated, electrohydraulically controlled multi-disc clutch. This set-up allows fully variable distribution of the drive torque between front and rear axles. Additional benefits of this design are a lower system weight than is available from the competition, and high efficiency.

Models with 4MATIC are equipped with DSR (Downhill Speed Regulation) and an off-road transmission mode as standard. DSR is activated by a control button in the centre console, and assists the driver on demanding downhill stretches by maintaining a slow, manually selected vehicle speed within the physical limits when negotiating downhill gradients. This is done with the help of the engine and transmission control systems, and by specific braking intervention.

When the off-road transmission mode is selected using the transmission mode switch, the gearshift points and accelerator characteristics are modified so that the requirements for driving on light off-road terrain and particularly loose surfaces can be met. In combination with Audio 20 CD (standard) and COMAND Online (optional extra), the head unit can also be switched to an off-road display. The steering angle, the selected off-road transmission mode and a compass are displayed there. The roll angle in degrees, the gradient in percent and activation of Downhill Speed Regulation DSR are also indicated.

Driver assistance systems. Numerous driving assistance systems offer support in the GLA and reduce the driver’s workload. Standard-fit features for the SUV include ATTENTION ASSIST drowsiness detection and radar-based COLLISION PREVENTION ASSIST with adaptive Brake Assist, which now helps to protect against collisions from a speed of only 7 km/h (4.3 mph).

This feature combines with DISTRONIC PLUS (optional extra) to become COLLISION PREVENTION ASSIST PLUS. This incorporates an additional function: When a danger of collision persists and the driver fails to respond, the system is able to carry out autonomous braking at speeds of up to 200 km/h (124 mph), thereby reducing the severity of collisions with slower or stopping vehicles. The system also brakes in response to stationary vehicles at a speed of up to 30 km/h (18.6 mph), and is able to prevent rear-end collisions at speeds of up to 20 km/h (12.4 mph).

Established assistance systems, such as the optional Lane Tracking package with Blind Spot and Lane Keeping Assist or Adaptive Highbeam Assist, are also available for the GLA. Active Parking Assist (optional) allows automatic parking in parallel and end-on parking spaces.

In the US market, the 2015 GLA250 4MATIC will go on sale in Fall 2014, followed by the 2015 GLA250 in early 2015. Pricing is still to be announced.

Source: Green Car Congress