When Nissan launched the Infiniti marque in 1991, it gave the company a chance to showcase all the technology it had been developing for the Japanese home market. The advancements would have made the Nissans too expensive for cost-sensitive buyers in America, Infiniti opened up a world of possibilities. For the flagship Q45, Infiniti introduced the world’s first full-active suspension at a cost of $4000, or $9500 in 2025 dollars).
The suspension rule of thumb is that you can either tune for bump-absorbing comfort at the expense of handling with a soft setup, or tune for controllable cornering at the expense of ride quality with a hard setup. With the full-active suspension, the idea was to provide the pillow-like ride of comfort-oriented luxury cars without sacrificing the dynamic performance that the Q45 excelled at.
Nissan had been working on active suspensions for years before the Q45. In 1985 it introduced the Super Sonic Suspension on the Laurel, Cedric and Gloria. It gathered data by adding an ultrasonic sensors on the shocks and used solenoids valves to control the dampers. Like modern drive mode selectors, drivers could turn the SSS to three hardness settings or automatic mode. Unfortunately, these models were never imported to the US.
The Infiniti Q45’s full-active suspension was the world’s first when it debuted in 1991. It used an array of g-force and vehicle height sensors to measure float, roll, dive and squat. A fast computer then parried with hydraulic actuators the forces acting on each wheel. It could raise or lower the suspension by 20mm and could self-level for heavy loads. It was incredibly advanced, but also incredibly complex.
The system added over 200 pounds to the Q45 and cost a whopping $4000 (approximately $9500 in 2025 dollars). It also dropped fuel economy by 10 percent. The only visual clues that a car was equipped with the system were the badge — Q45a for “active” instead of a plain Q45 — and a “Full-Active Suspension) sticker in the back window.
Today, it’s pretty hard to find a Q45 equipped with a functioning version of this system. Over time it develops leaks and pumps and actuator stop working, causing the suspension to droop. If so equipped, the fourth or fifth owner has likely already ripped it out and replaced it with a regular coil spring setup.
But how did the Q45a perform when new? In a 1991 Motorweek test, they took one to the track to put it through its paces. “Rumble and bounce normally associated with rough pavement was almost nonexistent,” they declared. It greatly reduced diving during hard braking and squatting during acceleration.
“In a slalom the rear end has less tendency to come around unexpectedly… it slides much easier,” they reported. It made the car feel more solid and not as heavy as you would think of a 4000-pound luxury sedan. Surface imperfections weren’t transmitted to the steering wheel nearly as much, but Motorweek says the feeling of connection to the road wasn’t really affected. That meant you could take a more aggressive line in cornering, braking later and accelerating sooner.
Car and Driver at the time said that it was better to take pass on the active suspension and go for the sport-tuned touring package instead. Sadly few of us will ever be able to experience the full-active suspension as it was intended to be. However, a version of it lives on in the Nissan Patrol and Infiniti QX80.
