Maybach Exelero (2005)

The designer mission was accomplished: The Exelero project is the ambassador of a new tire generation, the Fulda Carat Exelero in sizes up to 23 inches.

The Technic - German high technology and design aesthetics in perfection

Following the many model phases, whether it be the 1:1 study, the exterior design model as a reference for the form release, the interior reference model, the innumerable wind tunnel tests, the bodywork for the chassis in working order with subframe - eventually these phases of searching and coordination are concluded. Now it is time for the technicians and engineers.

Fulda's arguments were very clear right from the start:

• The reference vehicle for the new broad tire generation Exelero must withstand a constant load in use on the road, on the freeway, at trade shows, exhibitions and other events.
• The technically impressive values of the Fulda Gemballa show vehicle should serve as a guideline for the Exelero sports coupé.

The standard type 12 Maybach engine with Biturbo turbocharger produces 550 hp. Even this imposing engine cannot accelerate a vehicle weighing around 2.6 tons to a speed of around 350 km/h. A matter of honor for DaimlerChrysler's engine specialists in Untertürkheim. The designers dipped into their technical box of tricks and increased the cubic capacity from 5.6 to 5.9 liters. They further optimized the turbocharger and, lo and behold, the 700 hp and torque of at least 1,000 newton meters calculated for the desired speed was achieved. After around 100 hours of non-stop testing on the engine test bed, corresponding to a road test of about 15,000 kilometers, the unit was ready for use.

Leon Hustinx, the Director of Sales and Marketing at Maybach, was so impressed by the Exelero project that he quickly and unbureaucratically provided Fulda with the platform of a Maybach 57 limousine. How to conjuring up a sports coupé from it? For Jürgen Weissinger, head of development at Maybach, this was not the first tricky question. He is more familiar with the engineering of the Maybach than anyone else and, as project manager in pre-development, he has produced numerous feasibility studies for the make. When comparing the dimension concepts of the Fulda streamlined car of 1938 with the 57 platform, an astonishing correlation of measurements already emerged. Although today's Maybach is about 290 mm longer, e.g. in the wheelbase, the breadth and height of the veteran car strongly resembled the 57's dimensions.

That simplified construction considerably. Nevertheless, a great number of details had to be changed, among others:

• the driver's position including A-column and door had to be shifted back towards the rear axle;
• correspondingly the steering column and the pedals as well as the gear shift;
• a second front wall had to be integrated;
• the position of the tank remained unchanged, the refuelling nozzle had to be shifted etc..

All in all, however, the necessary changes were made in the short time available.

The development work connected with the rim and the wheel proved equally tricky. Rolf Dieter Stohrer, Senior Manager Car Tires and responsible for wheel and tire technology in the Fulda project team contacted several rim manufacturers and realized the rim called for in the design with Ronal. The corresponding design was milled by Ronal from a complete piece of metal, i.e. from a solid block weighing 257 kilograms a rim measuring 11.0 x 23 inches was produced with a weight of just 23 kg. All four rims were individually produced and because they are turbine wheels, the direction of movement had to be taken into account. Thus, two were produced for the left side and two for the right. However, these Ronal rims are only needed for the "See true" vehicle model. This is the exact copy of the Exelero sports coupé which, however, is not used in the road but merely at show events.

The real rims for the high speed tests come from ATP-Excentric in Bremen. The reason: the ATP rims have a cross spoke design which can be simply fully-panelled for the speed tests. This procedure means an additional 3-4 km/h for such gigantic 23-inch wheels. The air pressure of the tires will amount to 3.6 bar for the high speed tests. As a rim can bear a load of 1,050 kilograms, for example, the load on the rear axle of 1,400 kilograms is no problem, i.e. there is a sufficient reserve. After all technical requirements included in the engineers' specifications had been checked, the tests began.

The tests: 351.45 km/h, High speed record for 23-inch Exelero wide tires on Fulda/Maybach concept car

Sunday, 1 May 2005, 5.45 hrs., sunrise in a radiantly blue Southern Italian sky. The atmosphere is tense on Nardo's 12.5-kilometer circuit. Klaus Ludwig, a three-time DTM winner sits in his racing gear and helmet, apparently completely calm, at the wheel of the Maybach Exelero and waits for the signal to start in his attempt on the record.

This highlight of the project had been preceded by a number of intensive tests, starting with the various wind tunnel phases. In accordance with the results, the Exelero was optimized correspondingly.

Then in March came the roll-out in Turin where the Maybach Exelero was officially handed over to the client, Fulda Reifen.

In mid-April, it then went to the so-called "running-in track" at the Sindelfingen plant. Here, the vehicle was subjected to intensive checks of its engine functions, brakes, chassis and handling etc., already at speeds of around 200 km/h.

Finally, at the end of April, the technical inspection of the Exelero was carried out on the DaimlerChrysler test track in Papenburg, i.e. the test measurements conducted provided the basis for preparations for the attempt at the high speed record in Nardo. For example, Spoilers were tried out in various positions and further adjustments made to optimize the speed and stability.

Since the Exelero vehicle is intended to prove itself in the long run in practical use, it was appropriately designed as a road machine and needed a license. That meant that the TÜV (Technical Control Board) had to give its technical blessing to the Exelero. Peter Kühlwein, one of the most experienced experts of TÜV Automotive GmbH, Gruppe Süd, tested and evaluated the safety-relevant vehicle components like the seats with the safety belts and the weight distribution within the car. All points were checked off to the satisfaction of the TÜV engineer or otherwise reconfigured.

When all the reservations from the side of the DaimlerChrysler specialists, the tire engineers and the TÜV experts, had been satisfied, nothing stood in the way of the final mission in Southern Italy.

The entire team already arrived on Thursday. On this day and the next, the Exelero was completely checked yet again. On Saturday the team checked all the measuring facilities and conducted trial measurements as well as several test laps with technical project manager Jürgen Weissinger at the wheel. Early on Sunday morning then everything was ready: The final test could begin.

At 7.09 hrs., Klaus Ludwig already completed his first lap at a speed of 346 km/h. Just one lap later the targeted record of 350 was broken. The FIA standardized measuring unit registered a world record top speed of 351.45 km/h! Klaus Ludwig's comments after breaking the record: "It was unbelievable how easily the vehicle could be handled at this record speed. Particularly the tires conveyed an absolutely safe feeling. Everything was simply just right: technology, chassis and tires."

Bernd J. Hoffmann, Managing Director of Fulda Reifen, thanked all the teams involved for their outstanding efforts: "Everybody gave their best and thus made this success possible. The vehicle and tires supplement each other perfectly."