Accelerating with haste from a stop, the Q45 also delivers good highway passing and merging power. A test 2002 Q45 ran 0-60 mph in 6.7 seconds, versus Infiniti's claim of 5.9 seconds. A lower final-drive ratio promised to make the 2003 a bit punchier. Unfortunately, the transmission suffers frustrating early upshifts and tardy downshifts at full throttle. Intelligent Cruise Control works as intended, but it's most useful on uncrowded highways. Fuel economy is so-so. Early test cars averaged 15.9 to 16.6 mpg in a city/highway mix, and 19 mpg in mostly highway driving. A 2004 model average 18 mpg for similar usage. Premium fuel is required. While the Q45 rides comfortably in standard form, it fails to reach the top of the class. The suspension allows some float and bounce, yet impact harshness over small, sharp surface flaws is higher than the luxury norm. Little freeway thump is evident, though. Optional auto-adjusting shock absorbers have modest effect, though Sport mode may increase harshness. A Q45 corners acceptably for its size and weight, but it's less agile than most rivals. Steering feels rather vague, too. Auto-adjusting shocks, in Sport mode, might lessen body lean just a bit. Available 18-inch tires tend to wander along road grooves. Strong brakes make short, stable simulated-emergency stops. Road and wind noise levels are low overall, yet higher than expected for this class. The Premium model's 18-inch tires rumble more than 17s. The engine is smooth and quiet, even at high speeds. Crystal-clear gauges are pleasing, but the unnecessarily complex climate/audio/navigation setup takes time to learn and aggravates simple tasks like changing radio stations. The system often misinterprets voice commands, too. Interior materials are of good quality, but don't stand out for feel or visual panache. Front seats are comfortable, with generous head and leg room. Undersized outside mirrors hamper lane changes, but unique seven-lens headlights are among the brightest on the road. The standard power tilt/telescope steering wheel eases driver positioning. Infiniti's available rear-view TV system is outstanding in design and operation--best at revealing small objects just behind. However, the trunklid-mounted camera lens can be compromised by direct sunlight, heavy dust, raindrops, or salt spray. Although the Q45 trails an LS 430 or E-Class for stretch-out space, the back seat is surprisingly cozy, with just-acceptable six-footer head and leg room. The transmission hump and cushion shaping preclude a middle adult. Premium models add comfort-enhancing seat heating and a power reclining backrest. Trunk volume is below class-average, and intrusive trunklid hinges are an embarrassment at this price level. Cabin storage is plentiful.

Value for the Money
Premium sedans must deliver effortless performance in an atmosphere of uncompromised, spacious refinement. Materials and workmanship of the highest quality, along with at-your-service ergonomics, are also essential when a car costs as much as the Q45. Despite a good reliability record, the Q45 doesn't squarely hit any of these marks.