Mercedes-Benz CL 65 AMG and S 65 AMG

Press Release

Testing times: The development of the high-performance V12 Mercedes-Benz CL 65 AMG and S 65 AMG

• Pre-production testing at the DaimlerChrysler Papenburg proving ground
• Twelve hand-built prototypes underwent 13 months of road testing
• From the icy cold of Sweden to the desert heat of Arizona
• 30,000 km endurance test, 5000 km at the N??????????????????rburgring
• AMG V12 engine subjected to over 2500 hours of extreme testing

It is 6.30 a.m. at the high-speed circuit of the DaimlerChrysler Papenburg proving ground. Everything is quiet with not a car to be seen anywhere as the morning mist clears. The slightly hazy outline of a large Mercedes Coup?????????????????? appears on the horizon. As the dark-blue metallic test vehicle draws ever closer, the silence of the five-lane asphalt track soon gives way to the sound of a powerful engine combined with tyre and wind noise. Then, as quickly as it arrived, the CL 65 AMG disappears from view again. "High-speed Testing" is the official ??????????????????????????????????????? and eminently appropriate ??????????????????????????????????????? name of this phase of the development programme at the proving ground in Germany's Emsland region. Equipped with electronic measuring systems, a roll-over bar, a bucket seat and a four-point racing harness, the AMG test car is being driven by Klaus Ludwig, three-time winner of Le Mans and three-time DTM champion, who has been working as a consultant to DaimlerChrysler's development engineers since retiring from racing. After a 34-year career in international motorsport, it is hardly surprising that he remains imperturbable as the speedometer needle of the CL 65 AMG nears the 300 km/h mark. The 53 year-old former Mercedes-Benz works driver completes his final high-speed laps of the oval circuit before returning to the workshop where the engineers and specialists from Mercedes-AMG are already waiting. "Everything's fine; all the temperature and pressure readings are in the green zone", announces Klaus Ludwig. "It's very impressive: even at 260 km/h, the car still responds smoothly and effortlessly when you accelerate. You really feel you can make the most of its power out there on the high-speed circuit because all the safety-related components have been optimised to cope with it." Tobias Moers, who has overall responsibility for the development of the vehicle, and his colleagues Oliver Wiech (Team Leader - Cooling System/Fuel Tank), Michael Hanker (Control Systems Testing) are clearly pleased at this reassuring verdict. "We've been able to build up a wealth of data during the 15-month test programme", says Tobias Moers. "The extended trials we've conducted have allowed us to finalise the specification of the different components and software levels. Our work here in Papenburg focuses on optimising and approving the cooling, fuel and dynamic handling control systems so that series production of the CL 65 AMG and S 65 AMG can start on schedule."

The 12.2 km oval circuit: one of several test facilities at the DaimlerChrysler proving ground in Papenburg

This type of pre-production approval process is one of the principal activities at the DaimlerChrysler proving ground. In addition to the 12.2 km oval circuit, on which speeds in excess of 300 km/h can be attained safely, the AMG team can make use of the wet handling course and the dry handling course, the latter being a replica of the short track at Hockenheim. The following components and systems are the main subjects of the week-long tests which the AMG development engineers are conducting in order to confirm their ability to cope with highly dynamic driving situations:

• The newly developed charge-air cooling system with an air/water heat exchanger as well as the upgraded engine-oil cooling system of the AMG V12 biturbo engine.
• The electronically controlled fuel supply system with newly developed components.
• The completely reworked dynamic handling control systems such as ABS, Brake-Assist, ESP???????????????????? (Electronic Stability Program) and ASR; the new AMG high-performance braking system with composite discs on the front wheels involved additional development work.

Achieving the impressive engine performance figures represented a particularly interesting challenge, even for seasoned members of the AMG development team. One of the central development targets in the specification book was to deliver 450 kW/612 hp and 1000 newton metres of torque in a series production vehicle without compromising the high level of touring comfort traditionally associated with Mercedes. Tobias Moers comments: "As well as benefiting from our extensive experience in designing and developing high-performance cars, we found that AMG's long tradition in the field of motorsport was a major advantage. Our overall aim is to offer CL 65 AMG and S 65 AMG customers the highest possible degrees of performance and safety, whatever the operating conditions."

Dynamic handling tests on replica of the short track at Hockenheim

Once all the test results have been reviewed and the engine oil, tyres and brakes subjected to a routine check, Klaus Ludwig sets off in the silver CL 65 AMG for an hour-long test drive on the Papenburg handling course. The 2.6 km circuit is an exact replica of the short track at the Hockenheimring which developers have long regarded as the touchstone for judging a vehicle's handling, over/understeer characteristics and traction. He may not be battling it out with any other cars, but it is clear that Klaus Ludwig is enjoying taking the Coup?????????????????? (which is packed with highly sensitive electronic measuring equipment) to the limit as he alternates between full-on acceleration and hard braking on every lap. The tight Sachs curve, practically a 180 degree hairpin, is a punishing test for the tyres, transmission, chassis and ESP????????????????????. Thanks to the ABC chassis which has been optimised for AMG, body movement is kept to a minimum and there is no appreciable sensation of rolling in spite of the very high speed with which the car takes the corner. Klaus Ludwig's verdict after 50 laps: "You might think that a big Gran Turismo would be completely out of place here, but thanks to the new AMG set-up of the chassis, as well as the ABS, ASR and ESP???????????????????? systems, the CL 65 AMG is able to take the short Hockenheim track in its stride. I ought to mention the new, more powerful brake system as well. That's one of the things that makes this car such a good drive ??????????????????????????????????????? it's a lot of fun, too!" The driving style of the former DTM champion is reflected in the figures on the display of the laptop computer installed to the right of the centre console. Test engineer Michael Hanker assesses the readings it has picked up from the eight sensors built into the car. "The figures for lateral acceleration, yaw rate, steering angle and brake pressure as well as the four wheel-speed readings go straight to the ESP???????????????????? control unit. We analyse some 400 parameters by comparing them with the standard values. If there are any deviations, or if we're not satisfied with the way the vehicle is handling, we modify the software and off we go on the next test drive ", explains the AMG development engineer responsible for the dynamic handling systems.

The wet handling course: the moment of truth for ASR and ESP????????????????????

The V12 flagship model also passes the next test with flying colours. Klaus Ludwig wastes no time in taking the CL 65 AMG to the limit on the wet handling course where the sprinklers have been turned on. The ESP???????????????????? system remains activated ??????????????????????????????????????? after all, the objective is to establish if the new control algorithms and brake application patterns will still work as intended if the vehicle's road adhesion is suddenly compromised. The powerful V12 biturbo engine does not have the slightest difficulty in briefly overcoming the adhesion of the 275/35 R 19 rear tyres. But the ASR acceleration skid control system intervenes smoothly and effectively to keep the vehicle right on course. The warning light in the cockpit flickers into life momentarily before the full power of the engine is once again available. As he drives, Klaus Ludwig keeps glancing at the screen of the laptop fixed next to the centre console in order to check the various displays which indicate the status of the test sequence ??????????????????????????????????????? all the readings are just fine.

Acceleration and braking tests put the heat on the cooling system

While the former racing champion is discussing the results with head development engineer Tobias Moers in the workshop, Oliver Wiech sets out on another high-speed test run in the blue CL 65 AMG. After a number of laps at full throttle, the development engineer responsible for the cooling and fuel systems switches to a different test cycle: an alternating sequence of precisely defined acceleration and braking tests. This is particularly tough on the water cooling, charge-air cooling and engine-oil cooling systems, as no sooner has the CL 65 AMG negotiated the banked curve of the Papenburg oval circuit at 300 km/h than it is made to stand in the full heat of the midday sun with the engine running. "I keep the twelve-cylinder power plant idling to see the effect it has on the temperature of the engine coolant, the engine oil and the coolant circuit of the air/water charge-air cooling system", says Oliver Wiech. The AMG engineer can check no less than 228 different parameters with the on-board laptop. The most important ones are shown clearly on the display during the actual test and are also linked to a convenient "traffic light" indicator: "If a given limit is exceeded, the colour changes from green to amber, or even red in an extreme situation. This gives me the opportunity to interrupt the test immediately to look for the cause of the problem", explains Wiech. The first day of testing is over and everyone is happy with the way things have gone. There have been no unexpected problems requiring design changes or a major software update. But if the AMG Team are able to relax a little now, it is only because of all the design work, bench testing and road testing they have undertaken over the last two years. Development timeline:

• Engine design work begins in mid-2001
• First run of engine on a steady-state test rig in winter 2001/2002; basic mechanical analysis; study of oil circuit; power optimisation with various exhaust-turbocharger and camshaft variants; definition of exhaust-emission levels; injection quantity; charge-air ducting and regulation of boost pressure
• First in-vehicle endurance tests of engine in mid-2002
• First test-rig endurance tests of engine in autumn 2002

The 42 test engines ran for a total of 5500 hours on the test rig and also had to run for over 450 hours in the course of five in-car endurance tests which were conducted in order to verify the results. The results were drawn on continuously as the various engine components ??????????????????????????????????????? which initially existed only in the form of hand-made prototypes ??????????????????????????????????????? were refined and enhanced. Once the components were ready for series production, they were subjected to further endurance testing to ensure their quality. The same procedure was used for all the other components, such as the exhaust system, brake system, chassis, transmission and powertrain. The software which controls the engine, transmission and dynamic handling control systems was also optimised in successive releases. Overview of the principal phases of the standardised Mercedes-AMG test programme for the new CL 65 AMG and S 65 AMG: Development of engine, transmission and powertrain

• Altitude testing in Denver, Colorado (USA), Lesotho (South Africa) and Granada (Spain)
• High-temperature testing in Death Valley, California (USA), Upington (South Africa), at the Idiada test facility (Spain) and Phoenix, Arizona (USA)
• Test drives in Los Angeles, California (USA)
• Low-temperature testing in Arctic Falls (Sweden)

Development of cooling and fuel systems

• Various test drives on the high-speed circuits in Nardo (Italy) and Papenburg
• Testing in Upington (South Africa) and Death Valley, California (USA)
• Testing in the DaimlerChrysler wind tunnel

Development of brakes and control systems

• Testing of dynamic handling control systems at the Idiada test facility (Spain), in Arjeplog (Sweden) and at the Boxberg proving ground
• Testing of the DISTRONIC proximity control in Papenburg
• Testing of the brake system on the high-speed circuit in Nardo (Italy) and on the Grossglockner Pass (Austria)

It was also necessary to conduct endurance testing in order to compress an entire (and particularly punishing) vehicle lifetime into a short period:

• North Loop of the N??????????????????rburgring: The world's most demanding race circuit was used to test the vehicle, powertrain, chassis, wheel location elements and brakes. Total distance covered: 5000 km.
• Public road mix: Testing of interaction of all components and systems in everyday use. This test phase calls for the vehicles to be loaded to the permissible gross vehicle weight and to follow a precisely defined test programme comprising trunk roads, motorways and urban roads. Total distance covered: 120,000 km in four months.
• High-stress endurance testing at the DaimlerChrysler proving ground in Papenburg: Extreme acceleration and deceleration sequences with extensive full-throttle operation; places high level of stress on cooling and fuel supply systems. Total distance covered: 30,000 km in two weeks.
• "Swabian Alp" endurance test: The vehicles are loaded to the permissible gross vehicle weight and tow a two-tonne trailer; the route, which consists of trunk roads with many uphill and downhill gradients, places a high level of stress on the transmission and powertrain. Total distance covered: 25,000 km in four weeks.

Klaus Ludwig's verdict following the tests at Papenburg is equally positive: "At first, I thought that 612 hp and 1000 newton metres of torque would be too much of a good thing for a 'street legal' car. But having experienced it for myself, I can only compliment the AMG engineers on the fantastic job they've done developing the concept for series production. I was impressed to see how easily the car copes with such incredible power."