Stephen Mraz
Senior Editor

The Acura RL carried an impressive menu of intelligent safety features, enough to earn it the Highest IQ award in MACHINE DESIGN's Smart Ride competition.


Active Front lighting System (AFS) in the RL pivots the reflector in the headlamp to bend the low beams ±20° and illuminate the direction the driver is headed. The system determines where to shine the light based on vehicle speed and steering-wheel motion.

Active Front lighting System (AFS) in the RL pivots the reflector in the headlamp to bend the low beams ±20° and illuminate the direction the driver is headed. The system determines where to shine the light based on vehicle speed and steering-wheel motion.


The RL's navigation system takes inputs on 50 metropolitan cities to display traffic-flow information to the driver. Red indicates slow, possibly stopped traffic. Yellow is slow moving. And green is flowing normally.

The RL's navigation system takes inputs on 50 metropolitan cities to display traffic-flow information to the driver. Red indicates slow, possibly stopped traffic. Yellow is slow moving. And green is flowing normally.


The Acura RL could safely show off its adaptive cruise-control system when working with the test rig. The system keeps the car at a one of three driver-selected distances (near, medium, far) from the car in front, despite what the driver might have chosen as a cruising speed. The system uses a 1-lb radar unit transmitting at 77 GHz to track moving vehicles in front of the RL. It activates braking and adjusts the engine throttle to maintain a selected following distance.

The Acura RL could safely show off its adaptive cruise-control system when working with the test rig. The system keeps the car at a one of three driver-selected distances (near, medium, far) from the car in front, despite what the driver might have chosen as a cruising speed. The system uses a 1-lb radar unit transmitting at 77 GHz to track moving vehicles in front of the RL. It activates braking and adjusts the engine throttle to maintain a selected following distance.


At $54,000, the Acura RL was not the most expensive vehicle the judges had to evaluate, but it did seem to carry the longest list of intelligent features. And only one, the Collision Mitigation Braking System, was an option. The rest come standard on the RL (which is still dubbed the Legend in Asia and Europe).

Although judges appreciated the intuitive nature of the various features, one suspects they might rate the car even higher if given the chance to drive it for a month or more. For example, in a one-day test it's difficult to learn and appreciate a voice-recognition system that "understands" over 560 voice commands for the entertainment, HVAC, and navigation systems, among others. Honda worked closely with IBM on phonics-based voice recognition and advanced processing. As a result, the RL recognizes 1.7 million unique street and city names when spoken by a typical American, even if they have regional accents.

The RL shared many of the same features with other cars at the Smart Ride event, but in many instances, Honda engineers went the extra mile to make drivers more confident and deliver more usable information. The navigation system, for instance, not only includes the typical scrolling map on the center-console display and voice commands for upcoming turns, but also keeps drivers updated on potential traffic problems.

Honda is a partner with XM Satellite Radio and its XM Nav-Traffic service. It collects data on traffic flow, construction, accidents and even weather-related problems in the 50 largest metro areas. That data is processed and sent via a dedicated channel on XM's satellite network to various Acura vehicles, including RLs, MDXs, and TLs. The data shows up as red, yellow, and green highlights on roads where traffic is more stop than go, slow, and moving freely, respectively.

"The current traffic data is not what is should be," says Jim Keller, principal engineer at Honda. "It comes from helicopters, police, call-ins to radio shows, and other sources. We collect it, even it if is coarse and un-even. But it is improving. The system shows drivers what is happening, but does not plot an alternate route. We're currently working on a dynamic nav system that will give drivers three or four options to go around trouble spots."

Another system that benefits from Honda's extra efforts is Vehicle Stability Assist, their version of stability control. It takes inputs from the wheels (speed and slippage), as well as throttle setting, steering wheel motion and angle, and direction of motion, to determine where the driver is trying to steer the car. It then applies brakes independently to all four wheels and adjusts the throttle to ensure the car is moving in that direction.

The icing on the cake is that VSA gets to work with Honda's Super Handling-All-wheel Drive (SHAWD). Unlike AWD systems which alter the amount of torque sent to the front or rear wheels, SH-AWD also decides which rear wheel, left or right, gets the lion's share of the torque. In normal conditions, this means 90% of the torque goes to the front wheels. If the front wheels slip, however, a series of electromagnetic clutches sends up to 70% to the rear wheels. This helps in stability. But it also helps in cornering.

When accelerating through a right turn, for example, up to 100% of the torque sent to the rear goes to the left wheel. This generates an inward yaw which improves vehicle turn-in and reduces the rear-end's understeer. Similarly, when slowing through a turn, torque is varied to create an outward yaw in the outside rear wheel to keep the vehicle stable.

"SH-AWD was initially thought of as a performance upgrade, letting drivers safely increase cornering speeds. But in practice, it is more likely to let average drivers steer clear of emergency situations and avoid accidents, "says Keller.

One intelligent feature that was definitely developed solely for safety is the Collision Mitigation Braking System, the first collision-avoidance system that takes action even if the driver doesn't, according to Honda. It works with the radar module from the adaptive cruise system to track up to eight obstacles. CMBS evaluates the targets heading and speed, together with the RL's speed, yaw rate, and turning inputs, and the closing speed between the target and the RL to determine how likely a collision is. If it passes an initial threshold, the driver hears three beeps. If the driver takes no action and a crash becomes even more likely, the car activates the brakes three times and the seat belts tighten. If there are still no driver actions and the system determines a crash is imminent, it activates heavy braking and all the slack is pulled out of the seat belts.

"Almost all the features on the RL are standard, in keeping with Honda's motto, 'Safety for everyone,'" says Keller. "And this extends all the way through our product line to the Civic and Fit. They all have ABS, VSA, and the latest curtain and frontal, dual-stage air bags, as well as advanced collision-engineered bodies designed to handle frontal and offset impacts and not submarine under other vehicles in a crash. We make a big effort to standardize safety."