35 Years Ago, The Criminally Underrated Infiniti Q45a Gave America Its First Active Hydraulic Suspension

If you’re reading this website, you’re probably already familiar with how Lexus broke into the American market in the early 1990s, making a huge splash with its revolutionary LS400 sedan. The LS arrived on the scene with all of the same luxury appointments you’d find in a 7 Series or an S-Class, but for just a fraction of the price, and with a lot more reliability. The car’s rise to prominence is a widely known tale that you can read about in dozens of publications, including this website.

But Toyota, Lexus’s parent company, wasn’t the only Japanese brand that attempted to break into the luxury space in the 1990s. Nissan pulled a similar scheme starting in 1987 with the formation of Infiniti. Like Lexus, Infiniti launched in America with two cars; its goal was to encroach on the massive market share held by German luxury brands at the time.

Infiniti’s flagship car, the Q45 sedan, didn’t quite make the same impact as the Lexus LS. But it introduced the American public to a piece of tech that’s now ubiquitous in the modern luxury segment: Active suspension.

A Short History Of The Q45

The Q45 was one of many vehicles introduced by the Nissan brand following a huge overhaul of the company’s product line in the late 1980s. It was to lead the company to new heights in the U.S., joined by cars like the 300ZX, the 240SX, and the Maxima—all cars that have since outshined the Q45 in the automotive zeitgeist.

Infiniti’s big, luxurious sedan checked many of the same boxes as the LS. Both cars had naturally aspirated V-8s that sent power to the rear wheels, matching the layout offered by German competitors. The Q45’s was the VH45DE, a 4.5-liter unit that made 278 horsepower—28 more than the Lexus. The Infiniti even offered something the Lexus didn’t: Nissan’s well-known Super HICAS four-wheel steering system, included as part of the available Touring package, which also added forged alloy wheels and a rear spoiler.

Unlike the Lexus LS, which relied on stately, subdued lines, the Q45 was far more brash with its styling. In addition to the more rakish stance and sportier profile, early models famously came with no front grille. Designers told Car and Driver they spent twice as long finalizing the design as they normally would’ve on a new car. That time proved unproductive; while Lexus sold 41,000 LSs in the first year of production, Nissan sold just 14,000 Q45s, according to Consumer Guide. Infiniti would revise the front end to include a more traditional (and in my opinion, far less interesting) grille design for 1994.

The lower sales likely had something to do with the Q45’s price. While it was still far cheaper than anything with a Roundel or Tri-Star badge on the nose, the Infiniti was $3,000 more expensive than the Lexus, with a starting price of $38,000 ($93,718 in today’s money).

The Active Suspension Revolution

Active suspension aims to provide the best of both worlds. Using adjustable dampers or springs (or a combination of both, these systems can use a variety of sensors in the car to relay information to a computer, which can then adjust the suspension to better suit the vehicle’s situation. The ideal active suspension will deliver a soft, supple ride on rough roads, and a taught, stable ride on smooth roads or while driving quickly through corners.

Manufacturers began experimenting with active suspension systems as early as the 1970s, but like many forward-thinking pieces of car tech, it made its first debut in Formula 1. Lotus began development of an active suspension for its top-level race cars in 1981, before debuting it in 1983 at that year’s Brazilian Grand Prix. But it didn’t prove as effective as the company had hoped. From Motor Trend:

In theory, the system could raise cornering speeds considerably (Lotus engineer Peter Wright was famously quoted as saying its active-suspension F1 car could go around “any corner at any speed”), but in practice it reduced tire-slip angle so much that it was nearly impossible to get enough heat into the tires to allow them to function properly. The hydraulic system was also a bit of a horsepower pig, robbing 4 to 4.5 hp on a smooth road and up to 9 hp on a rough road. Add to that the computational complexity of the system and the need for aerospace-quality hydraulic actuators and you can start to see why this type of fully active suspension has yet to make it onto a mass-produced road car.

Still, automakers were determined to get active suspension tech into road cars. And so they did. As early as 1984, Nissan had a system called Super Sonic suspension, which used a sonar array mounted at the nose of the car and pointed at the ground to read the surface ahead of the tires. The sonar sensors would feed that data to the suspension, which would adjust damping as needed.

Mitsubishi was the first to get a true reactionary suspension system into a road car with its Electronically Controlled Suspension (ECS) in the Galant. That system was sold in Japan starting in 1987, before making its way to America through the VR-4 model in 1989.

The Q45 joined the Galant in 1990 to become among the first commercially available road cars in America with an active suspension system. Cars with the optional system were badged as the Q45a. Unlike the Mitsubishi setup, which used air springs, Nissan’s was hydraulically powered. In the above video, the always fantastic John Davis of Motor Week explains exactly how it works:

The Infiniti active suspension consists of an actuator at each wheel that does most of the work of the traditional shock absorber and spring. It is fed by an engine-driven oil pump. G sensors attached to a computer monitor the bounce, pitch, roll, and height of the vehicle. Signals are then sent to a pressure control unit that feeds hydraulic fluid to the wheel actuators as needed.

Pressure in some actuators may rise, while others are decreased. For instance, in a corner, roll is suppressed by increasing pressure to the actuators at the outer wheels and decreasing pressure at the inner wheels.

Basically, the system would react to the car’s position on the road and send hydraulic fluid to each corner individually to correct roll or pitch. That means in addition to lessening the severity of the Q45’s side-to-side lean, it could also improve dive angles under braking. It even had a “height” mode that could raise the car by 20 millimeters (0.78 inches) to clear particularly bumpy sections of road, not unlike an air suspension.

Davis, along with much of the automotive industry, praised the Q45a’s ability to deliver better handling, more stability, and superior performance over the standard Q45. On the surface, things were rosy. But like that Lotus mentioned earlier, things didn’t exactly work out.

Why Nissan’s Active Suspension Ultimately Disappeared

For one, Nissan’s system was expensive. It was offered on the Q45 as a standalone $5,000 option for the 1991 model year. That’s over $12,000 in today’s money, and would’ve been around a 10% increase in the car’s price out the door—not a great position to be in if the car is already more expensive than its closest competitor.

The system also added over 200 pounds to the Q45, according to Japanese Nostalgic Car. That hydraulic pump ran off the engine, so while it was improving handling, it was dragging down other parts of the car’s performance envelope. According to Motor Trend, the pump required 3 to 6 horsepower to run, adding 0.2 seconds to the Q45a’s 0-60 time, and slicing fuel economy by 2 mpg in the city and 3 mpg on the highway.

For most buyers, having a slightly better ride and slightly better cornering characteristics wasn’t worth the tradeoff. Infiniti expected just 15% of buyers to opt for the system when it was introduced, though it’s likely that fewer than that actually made the dive, as it was dropped altogether after the 1996 model year.

Still, the relevance of the Q45a can’t be overstated. It was the luxury segment’s first steps into the world of active suspension, paving the way for dozens of cars to offer similar systems for years to come. It was also ahead of the competition; Mercedes wouldn’t show off its first active suspension, the hydraulically-run ABC system, until 1996, when Nissan was phasing its system out of production.

These days, you can find several vehicles with adaptive hydraulic suspension. McLaren uses a version it calls Proactive suspension, which uses a series of chambers for the fluid to isolate road impacts, at the same time translating roll to the rest of the car through a series of interlinked piping. It’s so good at this that cars equipped with the system don’t need roll bars. Then there’s Porsche’s newest system, called Porsche Active Ride. Each corner gets its own electric pump that controls how much hydraulic pressure is in the damper, effectively eliminating roll, pitch, and dive. Incredibly cool stuff.

Top graphic images: Nissan