The smoothest cars on the highway are usually the tipsiest in the corners, while the flattest vehicles through the turns are spine-compressing buckboard wagons on the highway. Likewise, the highest-horsepower engines tend to be the worst guzzlers of fuel.
For the 2000 model year, automakers are harnessing the most sophisticated technology yet to attack these and other classic trade-offs in vehicle design.
For 2000, Mercedes-Benz introduces its Active Body Control on the flagship CL coupe. The system attacks the weighty CL's body roll, lift and dive without ruining its plush ride.
The suspension strut in each corner features a hydraulic ram that compresses or relaxes the steel spring on the strut. The system's computer takes readings from its 13-sensor array and reconfigures its settings every 10 milliseconds.
It directs the valves fed by the high-pressure hydraulic pump to open or close as needed to supply fluid to the strut.
By selectively loading and unloading the springs, the system keeps the CL's body more upright in corners and flatter during acceleration and braking.
General Motors takes a lower-cost route with its Stabilitrak 2.0 and continuously variable road-sensing suspension, improved with new software for the 2000 Cadillac DeVille DTS, Seville STS and Seville SLS.
Suspension supplier Delphi Automotive Systems Corp. has nicknamed the new software 'Wolf.' Its algorithms fine-tune the vehicle's manners and better integrate the suspension's operation with Stabilitrak, a Delco Electronics/Bosch system that selectively applies the brakes to keep the vehicle under control.
In the variable suspension, the springs are left alone. Instead, electronically controlled valves in the vehicle's otherwise conventional shock absorbers open and close to make the absorber softer or firmer as driving conditions dictate.
In a right turn, for example, the system firms up the left shock absorbers to reduce body roll and lessen understeer. The controller recalculates every millisecond and can recalibrate the shock absorber from full soft to full firm in just 9 inches of road travel at 65 mph.
Honda Motor Co.'s new S2000 roadster features a compact 2.0-liter four-cylinder engine that attacks the trade-offs among power, fuel efficiency and exhaust emissions. The all-aluminum, double-overhead-cam F20C engine generates 240 hp at a dizzying 8,300 rpm and 151 pounds-feet of torque at 7,500 rpm but returns an EPA mileage rating of 20 mpg city and 26 mpg highway.
It also meets California's low-emission vehicle standards, in part by using an electric air pump. The computer-controlled pump pipes air into the exhaust to feed an 'exothermic' burning of unburned gasoline, creating a blowtorch effect that quickly warms the catalyst.
The F20C engine is Honda's first with a crankshaft that rotates clockwise, bringing the company in line with the industry standard.
GM also has a new four-cylinder engine for 2000. The 2.2-liter L850 debuts on the new Saturn L, moving to the Opel Speedster and Astra later. The engine was developed jointly by GM's Powertrain division and Adam Opel AG subsidiary with help from Lotus Engineering.
The L850 is all aluminum with double overhead camshafts and 16 valves actuated by roller finger-follower lifters, which reduce friction in the valve train. Twin counter-rotating balance shafts stamp out vibrations, and engine accessories are hard-mounted to the block to reduce vibrations and noise chatter from brackets. The engine makes 137 hp at 5,800 rpm and 147 pounds-feet of torque at 4,400 rpm.
Toyota Motor Corp. puts a new spin on variable valve timing systems with the 2000 Celica. The car features an optional VVTL-i engine that adjusts both valve timing and lift using a system developed with Yamaha.
Both the intake and exhaust camshafts have two lobes per cylinder, one each for low- and high-speed operation. As the revs climb above 6,000 rpm, the computer directs pressurized oil to pins in the tappets that slide into place to activate the higher-lift, longer-duration lobe. Toyota claims the system adds 40 hp, giving the 1.8-liter four-cylinder engine a total output of 180 hp at 7,600 rpm.
The 2000 Audi TT introduces an all-wheel-drive system that eventually will be used throughout the Volkswagen AG lineup. This revised Quattro system uses electronic controls in combination with hydraulic clutches to distribute torque between the front and rear axles as road conditions require.
Supplied by Haldex Traction AB of Sweden, the clutches are mounted between the driveshaft and the rear differential. They are squeezed together with hydraulic pressure generated by a mechanical pump in the system that activates when there is a speed difference between the front and rear axle. A separate electric pump maintains a constant pressure, or preload, on the clutches so they will engage more quickly when needed.
A computer monitors wheel slip and engine speed, using the data to control a solenoid that regulates the hydraulic pressure against the clutches. Unlike other awd systems, this system does not wait around until the wheels start slipping. It can stay a half step ahead of the car based on the computer's read of the situation.
No electronics in this system. The 2000 Nissan Maxima picks up a bit of horsepower thanks to a variable back-pressure muffler on its 3.0-liter V-6 that relies on a spring-loaded valve. The muffler has one input pipe and two output pipes. The valve inside the muffler keeps the second outlet pipe closed until engine speeds climb above 2,000 rpm. When it opens, the second pipe cuts back pressure by up to 40 percent.
The Ford Taurus and Mercury Sable have been redesigned for 2000 and now include a Restraints Control Module to operate its dual-stage airbag inflator. The computer's sensors monitor the driver's seat position, whether the seat belts are buckled or not, and the accident severity. It uses the data to decide whether inflation is required and which inflation speed the front airbags should have to protect the occupant best.
The system also controls front seat belt pretensioners that reel in seat belt slack during the opening milliseconds of a collision to reduce injuries caused by the occupant jerking against the belt stops. Ford says the Taurus and Sable safety package could cut airbag deployments in half for the population of drivers who regularly wear seat belts.
Aaron Robinson is an Automotive News staff reporter based in Detroit