Technology with a purpose: Cadillac touts user-friendly advanced technology systems as key to new STS appeal

Automotive Industries,  July, 2004  by John McCormick

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After years of playing second fiddle to the competition in the upper luxury market, Cadillac is aiming for tier one status with its all-new 2005 STS.

Most importantly, the new flagship sedan from General Motors' luxury division switches from front-wheel-drive to rear-wheel or all-wheel-drive in order to compete effectively in a class dominated by rear-driven cars.

The STS adopts the Sigma architecture that has already proven successful in the Cadillac CTS sedan and SP, X sport utility, models. At 196 in. long, 72.6 in. wide and 57.6 in. high, with a 116.4 in. wheelbase, the STS is the largest of the Sigma family.

When the Lansing-built car reaches showrooms in the last quarter of 2004, buyers will have a choice of 320 hp Northstar 4.6L V-8 (in rear or all-wheel-drive configuration) or 255 hp 3.6L V-6 powertrain in rear drive only. Both engines feature variable valve timing (VVT) and use GM's electronically controlled five-speed automatic transmissions.

The Hydra-Matic 5L50-E is mated with the V-8, and the Hydra-Matic 5L40-E with the V6. Both transmissions incorporate driver shift control (DSC) and performance algorithm liftfoot (PAL) technologies.

Driver shift control enables the driver to switch from automatic to a clutchless five-speed high-performance manual transmission. Once the driver moves the gearshift lever into DSC mode, it operates with a fore and aft tap motion.

Performance algorithm liftfoot inhibits upshifts while maintaining engine braking following continuous aggressive driving. The transmission control module (TCM) monitors driver behavior to determine whether or not to enable this feature.

For example, if the system detects a drop in vehicle speed prior to entering a turn or a lane change, up to two downshifts can occur to provide the driver with maximum engine response.

The sophisticated suspension includes a two-mode magnetic ride (MR) control system, four-channel StabiliTrak, and an optional high-precision ZF steering gear.

The SLA front suspension uses aluminum for the upper and lower control arms, knuckles, and brake calipers, reducing overall mass and improving wheel control. Front shocks on base models are monotube dampers from ZF Sachs, while up-level versions offer the Delphi-developed MR system.

For crisper steering response, ZF's Servotronic II steering gear is available. This speed-sensitive steering gear has an 18.2:1 variable ratio, speed-sensitive variable assist, and a turning radius as little as 11.5 meters.

"Now we have legitimate hardware to go nose to nose with the competition," says vehicle line executive Jim Taylor, who lists the BMW 5-Series, 7-Series, Lexus GS300/LS430, Mercedes E-Class and Audi A6 among STS rivals.

Compared to the Japanese competitors, the STS will stress its performance edge, says Taylor. And versus the German rivals, the Cadillac's advantage will be its "purposeful technology," a reference to the well-publicized problems experienced by BMW and Mercedes with over-complex control ergonomics.

Along with its impressive array of powertrain and chassis hardware, the STS showcases a host of advanced convenience systems. The list includes keyless access with push button start, smart remote start, intellibeam and the Bose studio surround sound system, claimed to be the audio company's most sophisticated yet.

A crucial enabler for the STS's technology systems is an electrical backbone, known as a LAN (local area network) serial data system. This GM-developed electrical architecture comprises a high- and low-speed data network that connects system modules and ensures that information is properly communicated and shared between them.

In all, the STS is equipped with up to 27 modules, located throughout the vehicle, depending upon options selected. Each module sends and receives information sent via the LAN.

First introduced on the Cadillac XLR roadster last year, the keyless access/push button start system allows users to enter the STS and operate a push-button ignition with a personalized, keyless fob. With the key fob in a pocket or purse, the driver can approach a locked vehicle, pull the door handle and open the door.

The same concept applies when opening the trunk. As a result, the need to pull keys out--or even the fob--to activate the door and trunk functions has been eliminated. The system uses passive and active antennas to detect the vehicle fob and its proximity to the vehicle.

Once inside the vehicle, the fob-carrying driver's presence is detected by another set of antennas. The car's security, system checks the fob's code and allows the driver to start the engine with a short push of an instrument panel button.

Aside from requiring the fob to be inside the vehicle, the system also calls for the brake pedal to be depressed before the engine will start, as a means of preventing a child from operating the car.

A related system to keyless access is the STS's "smut" remote start. Using the fob, this operates from as far as 200 feet and not only starts the vehicle, but also automatically adjusts a variety of personalization settings in the process.