The first generation Infiniti FX was launched in 2003 as a sports utility vehicle. The vehicle was classified as a mid-sized vehicle meant for traveling in style. The FX replaced the QX4 in the lineup of Nissan. The FX came in two versions, each given a different number according to its engine. The FX35 derived its power from a 3.5 Liter V6 gas engine that had 24 valves and was available in rear-wheel drive and all-wheel drive configurations. It had a gear system with five automatic gears. The FX45 derived its power from a 4.5 liter V8 engine having eight cylinders and 32 valves. The FX was the first automobile to be installed with a system that warned the driver when they were about to change lanes when a traffic hazard exists.

In 2006, the Infiniti FX SUV became available with a new look in the front including a new grille, bumpers and newly designed tires. The FX still comes in two versions, the FX35 and FX45. The FX35 derives its power from 3.5 Liter V6 engine that has 280 horsepower. It is a rear-wheel drive vehicle but can be bought with an all-wheel drive option. It is equipped with leather seats, 18 inch tires, back seats that are split and can be reclined, airbags in the front and side for those sitting in the front seats, anti-lock brakes and TV monitor in the back. The FX45 is powered by a 4.5 Liter V8 engine and a gear system with five automatic gears. The vehicle is equipped with all-wheel drive. It has 20 inch tires, a cell phone that has Bluetooth connectivity, a seat for the driver with memory, headlights that switch on and off automatically and a system that can open all garage doors.

In 2008, the Infiniti FX will come in two new versions, numbered FX37 and FX50. The former will derive its power from a 3.7 liter V6 engine; the latter will derive its power from a 5.0 liter V8 engine.