By Bennett Oghifo
Abrisk lap of the race circuit or a weekend trip to the mountains with your sports gear stowed in the back: the new GLA 45 4MATIC+ (combined fuel consumption 9.2-9.1 l/100 km; combined CO2 emissions 211-209 g/km)1 and GLA 45 S 4MATIC+ (combined fuel consumption 9.3-9.2 l/100 km; combined CO2 emissions 212-210 g/km) are the assured masters of a multitude of disciplines. When required, these compact all-rounders can unleash a level of dynamic handling to impress even sports car owners. The 2.0-litre engine is the most powerful series-produced four-cylinder turbo engine and is available in two output and torque versions. Even the base model delivering 285 kW (387 hp) is more powerful than the previous model. The S-variant rated at 310 kW (421 hp) jostles with considerably higher vehicle classes. The active, fully-variable AMG Performance 4MATIC+ all-wheel drive distributes the power to the rear axle wheel-selectively by AMG TORQUE CONTROL, so providing the basis for top traction in any driving conditions. This is made possible by a new rear axle differential featuring two multi-disc clutches – one for each rear wheel. The AMG SPEEDSHIFT DCT 8G dual clutch transmission apportions the power within a split second to suit the specific driving situation.
“The second generation of our very successful compact sports model is now complete. The GLA portfolio, in the form of the Mercedes-AMG GLA 45 and GLA 45 S, now also includes our innovative four-cylinder turbo engine, so setting the benchmark in this segment. In addition, the new GLA 45 is not only significantly more dynamic, but also more practical in everyday use than its predecessor, thereby ensuring its appeal to a dynamic, lifestyle-oriented target group”, says Tobias Moers, Chairman of the Board of Management of Mercedes-AMG GmbH.
One new feature which makes a substantial contribution to the incomparable driving experience is the active, fully variable AMG Performance 4MATIC+ all-wheel drive: this system offers selective power distribution to the wheels on the rear axle via AMG TORQUE CONTROL. This means that the power is distributed to the left and right rear wheels flexibly and at different ratios, according to the given driving situation – resulting in optimum traction, whatever the road surface conditions and whatever course the route takes. This made possible by a redesigned rear axle differential featuring two multi-disc clutches, which selectively provide the flow of power to each individual rear wheel.
1 The stated figures were determined in accordance with the prescribed measuring method. These are the “NEDC CO2 figures” according to Article 2 No. 1 Implementing Regulation (EU) 2017/1153. The fuel consumption figures were calculated on the basis of these figures.
New four-cylinder turbo engine delivering superlative power
With an output of up to 310 kW (421 hp), the completely new Mercedes-AMG 2.0-litre engine is currently the world’s most powerful turbocharged four-cylinder manufactured for series production. Mercedes-AMG has improved on the output of the preceding engine by 30 kW (40 hp). Maximum torque has also increased, from 475 to as much as 500 newton metres.
The four-cylinder engine delivers extremely agile drive power in two output ratings: with 310 kW (421 hp) as the S-Model and with 285 kW (387 hp) in the base version. The new compact sports cars absolve the sprint from zero to 100 km/h in record time: the GLA 45 S 4MATIC+ requires just 4.3 seconds, while the base model GLA 45 4MATIC+ gets up to speed in 4.4 seconds. The top speed of the base model is electronically limited to 250 km/h, while the S-Model is allowed to leave the factory with a top speed of 270 km/h.
Apart from its pure performance figures, the new engine has an immediate response. To this end the torque curve was carefully balanced (“torque shaping”): The peak torque of 500 newton metres (480 newton metres for the base version) is available in a range of 5000-5250 rpm (4750-5000 rpm in the base version). With this configuration the AMG engineers have achieved a power delivery akin to a naturally aspirated engine.
Engine design featuring intelligent details
The new engine excels with numerous intelligent design features. In contrast to the likewise transversely installed four-cylinder in the 35-series models, the new engine has been turned around its vertical axis by 180 degrees. This means that the turbocharger and the exhaust manifold are now positioned at the rear, on the side of the firewall when viewed from behind. The intake system is therefore positioned at the front. This configuration allows the flattest possible and aerodynamically advantageous front section design. Furthermore, the new arrangement allows much improved air ducting with shorter distances and fewer diversions – both on the intake and exhaust side.
The new twin-scroll turbocharger combines optimum responsiveness at low engine speeds with a high power in the upper rpm range. The shaft of the compressor and turbine wheel is mounted for the first time on anti-friction bearings, so minimising mechanical friction in the turbocharger. The charger therefore responds even more readily and reaches its maximum speed of up to 169,000 rpm more rapidly. With a maximum charge pressure of 2.1 bar, the 2.0-litre four-cylinder turbo engine is also the leader in its segment in this respect. The electronically controlled wastegate (exhaust relief valve) allows the charge pressure to be controlled even more precisely and flexibly while optimising responsiveness, especially when accelerating from partial load. Numerous parameters are taken into account in this process.
Two-stage fuel injection for optimised performance
For the first time, the new high-performance four-cylinder has two-stage fuel injection. In the first stage the particularly fast and precisely operating piezo injectors supply fuel to the combustion chambers at a pressure of up to 200 bar. This is a multiple process at times, and is controlled by the engine management system as required. In the second stage there is additional intake manifold injection using solenoid valves. This is needed to achieve the engine’s high specific output. The electronically controlled fuel supply has an operating pressure of 6.7 bar.
