Toyota’s new Vehicle Dynamics Integrated Management (VDIM) system takes VSC one step further. Normally, VSC engagement is obvious to the driver, and not just because it beeps when a skid is about to occur. VSC can engage harshly, producing a vibration, a grinding noise, and sudden brake application.
VDIM, available today in the Lexus GS 430, Lexus RX 400h, and Toyota Highlander Hybrid, is planned to roll out across the entire Lexus, Scion and Toyota lineups in coming years, and is designed to perform the same function as VSC, but in a smoother manner. VDIM relies on the same set of sensors as VSC, but also takes into consideration signals carrying data about deceleration rates, brake pressure, brake pedal application, and wheel speed. Key to VDIM’s performance, because they create the electronic data upon which the system is dependent, are drive-by-wire steering and braking systems, and, on the GS 430, an active steering system that varies the steering ratio depending on vehicle speed.
To demonstrate the effectiveness of VDIM, Toyota provided us with Highlander SUVs on a dirt handling course and Lexus GS sedans on a wet, paved handling course. First we drove the Highlanders, lapping the course with VSC off, VSC on, and VDIM on. With VSC off, the Highlander was terrific fun, and we tossed it around like a rally car as we threaded the cones. But lots of people don’t think sliding a car around on a loose surface is terrific fun, especially when the sliding is unexpected, preferring instead the safety net of VSC. With VSC engaged, the Highlander reacted almost violently as we purposely dialed in too much steering, beeping and grinding and rocking and pitching in an effort to bring the SUV back under control. Plus, when we made an attempt to run the slalom smoothly and without VSC intervention, the system snapped to attention early – almost too soon.
In contrast, the Highlander Hybrid, with its VDIM system, behaved in a subtle manner, scrubbing less speed and correcting skids in a smoother, almost elegant fashion. The difference was plainly clear during a demonstration in which a professional driver screamed around a lengthy, winding, gravel test road located on the proving grounds, doing his best interpretation of pro-Rally driver Colin McRae as he pitched the Highlander into curves doing twice the speed that most people would consider prudent. Not only did this exercise highlight the leap in technology that VDIM represents over VSC, but it also underlined just how competent any stability control system is in preventing a wreck. And, it proved that driving, or riding in, a Toyota Highlander can actually be fun. Sometimes.
On the wet handling course, VDIM also proved its mettle. Lexus GS 300s with the standard VSC turned off regularly snacked upon cones, with at least one journalist performing a lurid 360-degree spin. With VSC on, the cone runners got to sit in their air-conditioned trucks, and we experienced the same sudden and intrusive butt-saving as we had in the Highlanders. The Lexus GS 430, with VDIM, allowed for smooth and rapid slaloming with barely a hint that the system was working to keep the GS pointed in the direction we wanted to go.
