2003 Dodge Viper SRT-10 Convertible

The Viper's sleek lines were designed to reduce drag, increase downforce, and improve engine cooling, resulting in somewhat more restrained styling than the original.

DaimlerChrysler's Dodge Viper sports car was notorious for a variety of reasons, but high technology wasn't among them. The all-new 2003 Viper doesn't exactly turn the elemental roadster into a high-tech showpiece, but the company had the resources in developing the car this time to significantly increase its sophistication.

The Viper retains its traditional aluminum overhead-valve V10 engine, but the revamped version now displaces 8.3 L and produces 373 kW (500 hp) and 678 N•m (500 lb•ft). Although outwardly similar, the new engine uses a new block, heads, and intake throttle body design. The car remains a front-engine, rear-drive machine, with a Tremec T-56 six-speed manual transmission the only available gearbox.

Power is delivered to the rear wheels unfettered by traction control or any stability control electronics, but a new Dana speed-sensing viscous differential renders those features almost unnecessary. Our test in the car at DaimlerChrysler's Arizona Proving Grounds showed that the differential makes the car's prodigious power very manageable, something that was decidedly not the case with the original car.

At 2510 mm (98.8 in), the wheelbase is 66 mm (2.6 in) longer and contributes to the car's improved stability. The longer wheelbase, restyled body, and underbody rear diffuser increase the car's aerodynamic downforce at high speeds. Revised suspension geometry reduces stiction under compression so the shocks control low-speed damping more precisely.

The aluminum 8.3-L OHV V10 employs an all-new block and heads to increase output to 373 kW (500 hp) and 678 N•m (500 lb•ft) of torque. Its central-mounted throttle body is a development from the successful Viper racing program.

As before, the Viper is built on a steel space frame, but the new frame is based on a large central backbone that contributes to a 35% improvement in torsional stiffness with 18 kg (40 lb) less mass. The central backbone design permits lower, narrower doorsills for easier entrance to and exit from the Viper. The resulting 1523 kg (3357 lb) curb mass compares to 1561 kg (3442 lb) for the outgoing RT/10 Roadster and 1578 kg (3479 lb) for the GTS Coupe. Bodywork remains plastic, but RIM replaces SMC in the fenders and quarter panels. SMC is still used for the doors, hood, and trunk lid.

Michelin continues as the exclusive tire supplier and partner for the Viper. The Pilot tires are now a run-flat design, freeing interior space that would have been dedicated to the spare tire. Front and rear wheel diameters are 18 and 19 in, respectively. Brembo supplies four-piston brake calipers and the anti-lock brake system. DaimlerChrysler said it debated whether ABS was appropriate for a basic sports car like the Viper, and it encountered some skepticism from owners. But testing convinced Team Viper engineers that ABS was the right choice, and the system was installed beginning with the 2001 model year.

The development team and Viper owners were tired of seeing the car lose magazine supercar comparisons because of long braking distances. The company's goal for the new model was to accelerate from 0 to 100 mph (160 km/h) and then brake to 0 mph again in 13.2 s, said Herb Helbig, Vehicle Synthesis Manager. In comparison, the original Viper needed 14.8 s to accomplish that, and the 2001 Viper, equipped with ABS, accomplished it in 14.2 s.

A new bi-fold clamshell-style folding convertible top supplied by Dura Corp. replaces the collapsible top from the previous roadster models, contributing to better all-weather protection and much more convenient top operation. In keeping with the car's character, the top is manually operated, but with a single center latch and easy-to-fold design, it marks a huge improvement over the previous design. A glass rear window with embedded defroster completes the upgrade.

When developing the new car, Team Viper members drew up a list of things they wanted to improve on the new car, said Helbig. "The top was right there at the head of the list," he said.

For improved forward illumination, Dodge installed xenon HID headlights on the new Viper, replacing the outgoing model's halogen infrared reflective bulbs.

Air management through the cockpit was a related issue the team addressed. The old car could be hot inside, and airflow was inadequate to keep occupants comfortable. The new car's HVAC system is designed along with the windshield and bodywork to ensure sufficient airflow while driving, without excessive buffeting. Small lipped edges on the A-pillars help control buffeting; we found that our ball cap stayed in place at even 210 km/h (130 mph). DaimlerChrysler's own 500-W stereo system with 6-disc CD changer proved clearly audible at that speed as well, so it seems likely to satisfy all but the most particular audiophile customers.

Interior ergonomics were improved by addressing fundamentals that, while obvious, were not possible in the original car because of its rapid development schedule and small budget. The steering wheel, driver's seat, and pedals in the old car were not square to the car's centerline. So it was no surprise drivers had difficulty getting comfortable in the car. The Johnson Controls-supplied seats in the '03 Viper are mounted straight in the car.

Despite the myriad improvements to the new Viper, it costs DaimlerChrysler $10,000 less to build than the old model, according to Helbig. Ensuring that the car could be built profitably was an absolute requirement under the company's current austerity program, he said.

One piece of trick technology that had been slated to appear on the Viper is absent from the production model. Active noise canceling mufflers were planned for the car to help it meet the conflicting requirements of low back-pressure and reasonable noise levels. The Viper is a particularly challenging case because, in a return to the car's original configuration, the 2003 Viper features side exhausts. The side exit makes the EPA's drive-by noise test especially difficult. Other problems with the side exhaust on the original car were an unflattering exhaust tone and extremely hot door sills because of the close proximity of the mufflers.

The solution in the new car was to route the exhaust pipes through the center of the car, connecting them with an H-pipe. This gives the car the longer pipes needed to help quell noise, while the H-pipe lets noise from both banks of the engine find its way out both sides, eliminating the five-cylinder drone of the older car.

Interior ergonomics were improved on the Viper by better aligning the steering wheel, driver's seat, and pedals.

Dodge moved from side exhaust to a rear exhaust on the earlier Viper in 1996, when stiffened EPA emissions requirements demanded an oxygen sensor downstream of the catalyst. On the Viper, that put the sensor too near the engine, and the water-resistant sensors of the time couldn't withstand the engine heat. Now, improved oxygen sensors have permitted a return to the side exhaust layout. With the central routing of the pipes, the problem of overheated doorsills has been eliminated too.

Dodge hasn't given up on the hope of still lower back-pressure through the use of electronic mufflers. "We're encouraging Tenneco to continue developing the system, because at some point we might want to come back to it," said Helbig.

The 2003 Viper is available only as a convertible, though the open-top model is as rigid as the discontinued coupe. A limited-production coupe will be available for racing, but so far there are no announced plans for general consumption. But that could change, according to Helbig. "It won't be a great leap to get from a convertible to a coupe," he said.

- Dan Carney

Mercedes-Benz E-Class

With a developing time of some 48 months, the new Mercedes-Benz E-Class represents an investment of about €2 billion ($1.7 billion).

The pace of design, development, and production of new models and the introduction of advanced technology from DaimlerChrysler show no signs of slackening, with the new Mercedes-Benz E-Class the latest proof. Unveiled at the Brussels Motor Show, the E-class's technology includes air to control springing and damping—very unusual in the car's segment—complementing four-link front and independent multi-link rear suspensions. Second-generation CDI turbodiesel engines—the four-cylinder with twin balancer shafts—are offered. Further diesels will be added to the range (probably including a V8), and a supercharged four-cylinder gasoline unit is planned. The Sensotronic electrohydraulic braking system fitted to the new SL is also used for the E-Class and now enters large-scale production. Safety elements include two-stage seatbelt force limiters and new crash sensors with automatic weight classification of the front passenger. The body structure has larger front deformation zones than the previous model. Mercedes has incorporated small amounts of magnesium in its cars for some years, and the E-Class uses the material for the dashboard crossmember.

The new car's styling carries over significant cues from the previous model but with more steeply raked headlamps (using projection-beam technology) and a generally less heavy and better-balanced signature. An E-Class option is a distinctive, panoramic glass roof. Aerodynamics for the new car was improved to 0.26 Cd (the previous E-class was already impressive at 0.27 Cd); CdA is 0.57 m² (6.1 ft²) compared to 0.58 m² (6.2 ft²).

A contribution to this excellent figure is a computer-based air control system positioned in the front bumper trim of some versions of the new car. Mercedes-Benz says the system consists of a compact plastic casing holding 16 electropneumatically adjustable louvers that stretch the length of the lower air intake. The system's controller analyzes various data such as road speed, coolant temperature, refrigerant pressure, and, depending on driving conditions and ambient temperature, decides whether additional cooling air feed is required. If it is not, the louvers close.

General levels of technology, quality, and performance of cars in the E-Class's segment have improved rapidly in recent years, in part to meet the needs of some buyers downsizing from cars in the large executive range (e.g., Mercedes-Benz S-Class, BMW 7 Series, Audi A8, Jaguar XJ8) but still expecting similar standards of ride, comfort, and overall equipment. These changes have cascaded down the sedan range, so the C-Class is in some senses a downsized E-Class (but with very clear aesthetic links to the much bigger and more prestigious S-Class).

The new E-Class has an exceptionally low Cd of 0.26.

Developed in about 48 months, the car required an investment of about €2 billion ($1.7 billion), 50% of which was spent at the Mercedes Sindelfingen plant.

In this vehicle segment, there is a need to create a car that meets several criteria, mixing executive-car requirements with sporty handling, and in some versions (including taxis), low fuel consumption. The need to meet such diverse requirements is a design challenge, and Mercedes-Benz is aware of the previous car's success, with sales reaching 1.4 million units from its introduction in 1995.

The bodyshell of the new car is about 18% stiffer than that of its predecessor. To reduce weight, Mercedes-Benz used aluminum for the hood, front fenders, trunk lid, front end module and module carrier, rear end module, parcel shelf, and the panel behind the rear seat backrest (on models with a single section seat unit). For Mercedes-Benz, this is extensive use of aluminum, which for the E-Class accounts for about 10% of bodyshell materials by weight. High-strength steel, also a weight-saver, represents about 37%, and plastics only 1% (there is a plastic spare wheel well), with the remainder of the car using regular steel.

About 10% of the new E-Class's body uses aluminum.

The E-Class adopts Mercedes' modular design concept applied to other models. It simplifies both body assembly and in-service bodywork repairs. The front- and rear-end modules are bolted together with the bodywork structure, allowing them to be placed without the need for lengthy welding work should they become damaged in an accident. Even the individual components contained within the modules are bolted together. The front-end module features a strong aluminum crossmember. This reinforces the front bumper, and in the event of a frontal offset impact redirects the forces of the side not subject to any direct load, thereby playing a definitive role in the absorption of impact energy. A pair of aluminum crash boxes forms an energy-absorbing link with the front side members. The rear-end module has a high-strength flexible aluminum crossmember connected to the structure by two steel crash boxes. The car's main floor assembly uses three different laser-welded tailored blanks, the central 1 mm (0.04 in) thick blank forming the transmission tunnel.

A new, flexible rolling technique is used to manufacture the two connecting members that extend the front side members back into the structure of the floor assembly to provide material thickness and stability. The high-strength steel can be machined at the rolling plant to provide different panel thicknesses in a single component. Mercedes-Benz believes it is the first time that a "flexible rolling technique" has been used in large-scale series manufacture.

Mercedes-Benz has given the E-Class a higher level of body rigidity than that of the previous version—although it does not quote figures—with a solid crossmember beneath the front seats, a load-bearing section between both B-pillars, and reinforcement paneling in the footwells, plus the flexibly rolled connecting members. In addition, there is a continuous firewall crossmember linking the two side wall panels. Each forms a single section but is made of a number of panel blanks that are laser-welded together and then formed into the desired shape.

Safety systems on the new car include two-stage airbags and belt force limiters. There are two sensors positioned on the radiator crossmember linked to an electronic control module to provide early warning of impact severity, which not only allows belt tensioners to activate but also controls front seatbelt force limiters adaptively. The restraining force of the belt strap can be reduced progressively. Should the sensors relay information indicating a severe frontal collision, the belt will first be pulled taut until it reaches maximum tension. The belt force limiters switch to a lower tension a moment later; the extra slack in the seat belts allows the occupants in front to fall deeper into the airbags, reducing the loads exerted on their chests.

New seat designs for the E-Class include a dynamic multi-contour type for added cornering support.

Mercedes-Benz joins other manufacturers in using magnesium as a cross-beam "anchor" for the dashboard and its components, which include radio, climate control, instrument cluster, and steering column. An unusual interior feature is a powered flip-up switch panel facilitating access to the CD changer or stowage compartment located behind it. Thirty seconds after use, it pivots away again. The car has a Keyless-Go electronic driver recognition system.

Four-zone climate control is available for the E-Class. Air distribution involves the use of a dozen electric motors under the control of a microcomputer fed by several sensors. It processes information on interior, ambient, and coolant temperatures, and takes note of side window and sunroof position. According to Mercedes-Benz, measuring the amount of sunlight being radiated into the vehicle is important. This is monitored by a four-quadrant solar sensor on the hood that regulates airflow and temperature for each of the four seats, depending on the angle of incidence of the sun's rays.

A panoramic sliding sunroof is a new option for the E-class and is similar to the design used for the C-Class Coupe. It has twice the surface of a conventional tilting/sliding system. Its glass surface stretches almost completely from the windshield header rail to the top of the rear windshield. Mercedes says that 100% of UV-B and UV-C light is filtered out, with only 2.2% of UV-A light entering the car's interior. The panoramic roof has a two-section powered roller blind.

Airmatic DC controls springing and damping and complements the E-Class's multi-link rear and new four-link suspension.

The E-Class can be specified with a "dynamic multicontour seat" fitted with air cushions and linked, via electropneumatic control and a microcomputer, to inputs including steering angle, lateral acceleration, and road speed. In a left turn, the right-side cushions inflate. The seat has a pulsing massage function, and active ventilation is fitted.

The air suspension, fitted to the E 500 and available on other versions, is a development of that from the S-Class first used four years ago. It is called Airmatic DC (Dual Control) and is particularly significant in controlling both springing and damping. Rubber bellows filled with compressed air are fitted in the spring struts to control the springing function. Normal pressure in the system is in the range of 700 to 900 kPa (100 to 130 psi). By active air volume control, Airmatic DC is able to provide a harder spring rate with pitch and roll reduced. To achieve this, the system deactivates a portion of the air volume. The ride softens when total air volume is active.

The air system complements a new four-link front axle setup instead of just double wishbones used on the previous E-Class. The role of the lower wishbone is now controlled by two separate links: torque strut and spring link. Two link levels are connected to one another by steering knuckles. The fourth element, which gives the four-link its name, comprises the track rods. As well as providing improved handling, ride, and directional stability, the system allows greater deformation in the environs of the lower link in the event of a head-on collision. The multi-link rear axle is the same as that used for the previous E-Class, but when equipped with Airmatic DC, all links use forged aluminum. For non-Airmatic cars, the spring link uses sheet steel. It is a standard fit.

E-Class diesels get a variable-geometry turbocharger.

The E-Class comes with a wide choice of powertrains—with more in prospect. Five gasoline engines are available (V6 and V8) and two turbodiesels (CDI) with four and five cylinders. The diesels are second-generation common-rail units, incorporating about 80 new components. They now have a VNT turbocharger with variable-geometry guide vanes that are electrically rather than vacuum-controlled. The in-cylinder gas cycle has been improved and maximum firing pressure upped from 14.5 to 15.5 MPa (2100 to 2250 psi).

These changes have enhanced available low-end torque, the five-cylinder E270 CDI now offering 205 N•m (151 lb•ft) at 1000 rpm, 350 N•m (258 lb•ft) at 1400 rpm, and maximum torque of 425 N•m (313 lb•ft) at 2000 rpm. Fuel consumption is reduced by 0.4 L/100 km. A seven-hole injector nozzle (previously six) allows for a 20% reduction in nozzle hole diameter. Fuel flow rate is down and so are particulates. Injection pressure has been upped from 135 to 160 MPa (19,600 to 23,200 psi) to shorten the injection period and compensate for the effect of flow restriction at higher revs due to the smaller nozzles.

Balance shafts are used in the four-cylinder 2.2-L diesel engine. The V6 and V8 gasoline engines are established units. The V8 E500 has an output of 225 kW (302 hp) and provides a provisional 0 to 100 km/h (0-62 mph) acceleration time of about 6 s. Manual gearboxes are six-speed, automatics five-speed.

- Stuart Birch