Which Infiniti Q45 Version Should You Buy?
The Infiniti Q45 choice comes down to three distinct specifications. The 2004–2006 restyled third-generation 4.5 AT and the 2001–2004 third-generation 4.5 AT provide the strongest performance: 340 hp, 451 Nm, a 5-speed Automatic transmission, and 0–100 km/h in 5.9 seconds.
The Infiniti Q45 choice comes down to three distinct specifications. The 2004–2006 restyled third-generation 4.5 AT and the 2001–2004 third-generation 4.5 AT provide the strongest performance: 340 hp, 451 Nm, a 5-speed Automatic transmission, and 0–100 km/h in 5.9 seconds. The 1996–2001 second-generation 4.1 AT is less powerful at 269 hp and slower at 7.9 seconds, but it has the lowest kerb weight at 1,760 kg. The 1989–1996 first-generation 4.5 AT occupies the middle ground with 278 hp and the highest listed top speed, 241 km/h. Every version is a Sedan with a naturally aspirated Gasoline V-shaped 8-cylinder engine and RWD.
Infiniti Q45 generations: what changed?
The first-generation Infiniti Q45, produced from 1989 to 1996, was offered here as one Sedan version, the 4.5 AT. Its 4,494 cc engine produces 278 hp at 6,000 rpm and 396 Nm at 4,000 rpm. It uses a 4-speed Automatic transmission and RWD. At approximately 61.9 hp per litre, it is less highly tuned than the later 4.5 AT, but its listed maximum speed of 241 km/h is the highest in the data.
The second generation ran from 1996 to 2001 and also contained one Sedan version: 4.1 AT. Its engine capacity fell to 4,130 cc, while output was 269 hp at 5,600 rpm and 378 Nm at 4,000 rpm. Power density rose slightly to approximately 65.1 hp per litre. This generation retained the 4-speed Automatic transmission and RWD, and its 1,760 kg kerb weight is the lowest among the listed Q45 versions.
The third generation was produced from 2001 to 2004, followed by a restyled form from 2004 to 2006. Both periods contain one Sedan version named 4.5 AT, and both share the same principal engine and performance figures: 4,494 cc, 340 hp at 6,400 rpm, 451 Nm at 4,000 rpm, a 5-speed Automatic transmission, RWD, 0–100 km/h in 5.9 seconds, and a 230 km/h maximum speed. The restyled car is 60 kg heavier, with kerb weight increasing from 1,820 to 1,880 kg, while its gross weight falls by 22 kg, from 2,350 to 2,328 kg.
Infiniti Q45 engine and specs comparison
| Generation and years | Exact version | Engine | Power | Torque | Fuel | Cylinders and layout | Boost | Gearbox | Drive |
|---|---|---|---|---|---|---|---|---|---|
| First, 1989–1996 | 4.5 AT | 4,494 cc | 278 hp | 396 Nm | Gasoline | 8, V-shaped | No | 4-speed Automatic | RWD |
| Second, 1996–2001 | 4.1 AT | 4,130 cc | 269 hp | 378 Nm | Gasoline | 8, V-shaped | No | 4-speed Automatic | RWD |
| Third, 2001–2004 | 4.5 AT | 4,494 cc | 340 hp | 451 Nm | Gasoline | 8, V-shaped | No | 5-speed Automatic | RWD |
| Third, restyled, 2004–2006 | 4.5 AT | 4,494 cc | 340 hp | 451 Nm | Gasoline | 8, V-shaped | No | 5-speed Automatic | RWD |
The clearest mechanical step occurs between the second-generation 4.1 AT and the third-generation 4.5 AT. Displacement rises by 364 cc, power increases by 71 hp, and torque grows by 73 Nm. The transmission also gains one forward speed. Compared with the first-generation 4.5 AT, the third-generation 4.5 AT extracts 62 hp and 55 Nm more from the same 4,494 cc displacement. Its approximate output of 75.7 hp per litre is 13.8 hp per litre higher than the first generation’s 61.9 hp per litre.
All four engines use Distributed injection (multi-point), with 4 valves per cylinder and No boost. The first-generation 4.5 AT has a compression ratio of 10.2, while the other listed versions use 10.5. The third-generation and restyled third-generation engines are mounted Front, longitudinal. Engine position for the first- and second-generation versions is not measured.
Infiniti Q45 performance, acceleration, and economy
| Generation and exact version | 0–100 km/h | Top speed | City consumption | Highway consumption | Combined consumption |
|---|---|---|---|---|---|
| First, 4.5 AT | not measured | 241 km/h | not measured | not measured | not measured |
| Second, 4.1 AT | 7.9 seconds | 232 km/h | not measured | not measured | not measured |
| Third, 4.5 AT | 5.9 seconds | 230 km/h | not measured | not measured | not measured |
| Third, restyled, 4.5 AT | 5.9 seconds | 230 km/h | not measured | not measured | not measured |
For acceleration, either third-generation 4.5 AT is the straightforward choice. Its 5.9-second time is 2.0 seconds quicker than the second-generation 4.1 AT. The two third-generation specifications are tied on power, torque, acceleration, and maximum speed, so the restyling does not produce a numerical performance advantage in the supplied data.
For maximum speed, the first-generation 4.5 AT leads at 241 km/h. That is 9 km/h above the second-generation 4.1 AT and 11 km/h above either third-generation 4.5 AT. Its 0–100 km/h time, however, is not measured, so it cannot be ranked fairly for acceleration.
City, highway, and combined fuel-consumption figures are not measured for every version. CO₂ output and environmental class are also not measured. Consequently, the supplied specifications do not support a fuel-economy or emissions-based recommendation.
Infiniti Q45 weight, size, wheels, and tank capacity
| Generation and exact version | Kerb weight | Gross weight | Weight per hp | Ground clearance | Tank | Wheel sizes |
|---|---|---|---|---|---|---|
| First, 4.5 AT | 1,833 kg | not measured | approximately 6.59 kg/hp | 145 mm | 85 L | not measured |
| Second, 4.1 AT | 1,760 kg | 2,355 kg | approximately 6.54 kg/hp | 140 mm | 85 L | not measured |
| Third, 4.5 AT | 1,820 kg | 2,350 kg | approximately 5.35 kg/hp | 140 mm | 85 L | 225/55 R17 or 245/45 R18 |
| Third, restyled, 4.5 AT | 1,880 kg | 2,328 kg | approximately 5.53 kg/hp | 140 mm | 85 L | 225/55 R17 or 245/45 R18 |
The 2001–2004 third-generation 4.5 AT has the best power-to-weight result, carrying approximately 5.35 kg for each horsepower. The restyled 4.5 AT carries approximately 5.53 kg per horsepower because it retains 340 hp while gaining 60 kg. The second-generation 4.1 AT is 60 kg lighter than the pre-restyling third generation, yet its lower output leaves it with approximately 6.54 kg per horsepower.
Every version has an 85 L fuel tank. The first-generation 4.5 AT provides the greatest listed ground clearance at 145 mm, which is 5 mm more than the other versions. Wheel sizes are not measured for the first and second generations. Both third-generation periods list 225/55 R17 and 245/45 R18.
Exterior length, width, height, and wheelbase are not measured in the supplied data. Although shoppers frequently compare Infiniti Q45 dimensions and overall size, those values therefore cannot be stated here.
All versions use Independent, spring front and rear suspension. Each has Ventilated disc front brakes and Disc rear brakes, so these specifications do not distinguish one generation from another.
Infiniti Q45 reliability and problems
Reliability records, service histories, component failure rates, and problem reports are not measured in the supplied data. No version can therefore be described as more reliable than another. The available specifications can compare engine output, performance, transmission, weight, clearance, wheels, and capacity, but they cannot establish maintenance cost or long-term durability.
Which Infiniti Q45 version should you buy?
Choose the 2001–2004 third-generation 4.5 AT when the priority is the strongest numerical all-round specification. It matches the restyled car’s 340 hp, 451 Nm, 5.9-second acceleration, and 230 km/h maximum speed while weighing 60 kg less. Its approximately 5.35 kg/hp figure is the best in the range.
Choose the 2004–2006 restyled third-generation 4.5 AT if the later production period matters more than the extra mass. It offers no measured engine or acceleration gain over the 2001–2004 car, and its weight-to-power figure is slightly less favorable. The data contains no equipment, reliability, or price figures that could identify what else the later version provides.
Choose the second-generation 4.1 AT if the lowest kerb weight is the main criterion. At 1,760 kg, it is 60 kg lighter than the early third generation, 120 kg lighter than the restyled third generation, and 73 kg lighter than the first generation. The trade-off is explicit: it has the lowest output at 269 hp and 378 Nm, plus the slowest measured 0–100 km/h time at 7.9 seconds.
Choose the first-generation 4.5 AT for the highest listed maximum speed and greatest ground clearance. Its 241 km/h maximum and 145 mm clearance lead the supplied figures, while its 278 hp places it 9 hp above the second-generation car but 62 hp below either third-generation version. Because its acceleration, gross weight, and wheel sizes are not measured, it is the hardest version to compare comprehensively.
On specifications alone, the 2001–2004 4.5 AT is the strongest buy: it combines the highest power and torque with the joint-fastest measured acceleration and the best calculated weight per horsepower. A purchase decision based on condition, reliability, or value would require inspection, history, and pricing information that is not present in the data.