Infiniti M

Infiniti M: generations: what actually changed between years

Five generations sit in the catalogue. Body type is Sedan from 2nd through 4th generation; only 1st generation is Cabrio.

Five generations sit in the catalogue. Body type is Sedan from 2nd through 4th generation; only 1st generation is Cabrio.

1st generation (1989–1992), Cabrio. Two rows, both named 3.0 AT, both 164 hp / 121 kW, 3000 cm³ Gasoline, 6 cylinders, V-shaped, boost No, Automatic, 4 gears, RWD. Ground clearance 160 mm — the highest in the whole model. Rear suspension is Dependent, spring; later generations are Independent, spring at both ends. Torque, 0–100, top speed, fuel use, tank, kerb mass and wheels are not measured on either row. The two 3.0 AT lines match on every field that is filled, so the catalogue does not separate them by power or drive.

2nd generation (2002–2004), Sedan. One version: 4.5 AT, 344 hp / 253 kW at 6400 rpm wait - I must not invent rpm. Check: power was not printed for gen2. I didn't extract rpm for gen2. Don't invent.

2nd gen 4.5 AT: 344 hp, 451 Nm, 4494 cm³, 8 cyl V-shaped, Automatic 5, RWD, 5.8 s, 235 km/h, kerb 1790 kg, GVM 2190 kg, clearance 140 mm, tank 85 L — largest tank in the model. Consumption not measured. Wheels not measured.

3rd generation (2005–2008), Sedan. Three versions. Two 3.5 AT at 280 hp (RWD and AWD) and one 4.5 AT 340 hp RWD. Tank drops to 75 L (−10 L vs 2nd generation). Clearance 130 mm on all three. Wheels measured: 245/45 R18 and 245/40 R19 on all three. Gearbox is Automatic 5 on all three.

3rd generation, restyling (2008–2010), Sedan. Seven versions. The same 3.5 AT name covers 280, 303 and 307 hp; 4.5 AT stays 340 hp but splits RWD and AWD. Tank 76 L. A 7-speed Automatic appears on the 307 hp 3.5 AT RWD and the 303 hp 3.5 AT RWD; AWD rows stay 5-speed except where listed. Top speed on AWD 307 hp and AWD 280 hp is 206 km/h versus 250 km/h on several RWD/AWD 303/307 rows.

4th generation (2010–2013), Sedan. Six versions: 2.5 AT, two 3.7 AT (AWD and RWD), two 5.6 AT (AWD and RWD), one 3.0 AT Diesel. Displacement steps 2496 / 2993 / 3696 / 5552 cm³. All use Automatic 7. Tank 80 L. Clearance 144–149 mm, up from the restyle’s 124–140 mm band. Euro 4 on four petrol rows; Euro 5 on 3.0 AT Diesel and 3.7 AT RWD. Only 5.6 AT uses Direct injection (direct) and 8 cylinders; the V6 petrol rows use Distributed injection (multi-point). Only the Diesel has boost Turbo.

Across generations the 4.5-litre eight-cylinder leaves after the restyle; the 4th generation replaces it with 5.6 litres (408 hp vs 340–344 hp). Specific output of the 4th-generation 3.7 AT is 333 / 3.696 ≈ 90.1 hp per litre; the 5.6 AT is 408 / 5.552 ≈ 73.5 hp per litre; 2nd-generation 4.5 AT is 344 / 4.494 ≈ 76.5 hp per litre; 1st-generation 3.0 AT is 164 / 3.000 ≈ 54.7 hp per litre.

Engines and specs

Same name, different cars: in 4th generation the two 3.7 AT rows are 333 hp both, split by AWD (363 Nm, Euro 4) versus RWD (366 Nm, Euro 5). The two 5.6 AT rows are both 408 hp / 550 Nm, split by AWD versus RWD. In the restyle, 3.5 AT is 280, 303 or 307 hp — use horsepower, then drive, then gear count. The 303 hp pair has 268 Nm; the 307 hp and 280 hp rows have 363 Nm. Pre-restyle 3.5 AT is only 280 hp.

Fuel octane on measured petrol rows is 95 except where not measured (1st generation 3.0 AT). Diesel fuel on 4th-generation 3.0 AT is Diesel.

Performance and economy (0–100, top speed, mpg-style L/100 km)

Fastest 0–100 in the model: 4th-generation 5.6 AT RWD at 5.2 s. AWD 5.6 AT is 0.2 s slower (5.4 s). Restyle 4.5 AT AWD is 5.8 s — same time as 2nd-generation 4.5 AT RWD (5.8 s), despite 340 hp versus 344 hp. Slowest measured sprint is 4th-generation 2.5 AT at 9.2 s: 4.0 s behind the 5.6 AT RWD, with 186 fewer horsepower (408 − 222).

Diesel versus small petrol in 4th generation: 3.0 AT 238 hp reaches 100 km/h in 6.9 s; 2.5 AT 222 hp needs 9.2 s. The diesel’s 550 Nm arrives at 1750 rpm; the 5.6 AT also makes 550 Nm, but at 4400 rpm. Mixed consumption: 3.0 AT 7.5 L/100 km versus 2.5 AT 9.9 — 2.4 L/100 km less for the diesel, and 3.0 L less than 3.7 AT RWD (10.2), 3.4 L less than 3.7 AT AWD (10.9), 4.5 L less than 5.6 AT RWD (12.0), 5.0 L less than 5.6 AT AWD (12.5).

Highway: diesel 3.0 AT 5.9 L/100 km; 2.5 AT 7.9; 3.7 AT RWD 7.4; 3.7 AT AWD 8.4; 5.6 AT RWD 8.8; 5.6 AT AWD 8.9. City: diesel 10.3 versus 5.6 AT AWD 18.7 — 8.4 L/100 km more in town for the V8 AWD.

AWD tax inside 4th generation 3.7 AT: +0.1 s (6.3 vs 6.2), +0.7 L mixed (10.9 vs 10.2), top speed 246 vs 250 km/h. 5.6 AT AWD vs RWD: +0.2 s, +0.5 L mixed, same 250 km/h.

Restyle 3.5 AT 307 hp RWD 7-speed: 6.4 s, 250 km/h, mixed 12.6 L/100 km. Same 307 hp AWD 5-speed: 6.7 s (+0.3 s), 206 km/h (−44 km/h), mixed 13.6 (+1.0 L). Restyle 3.5 AT 280 hp AWD: 7.1 s, 206 km/h, mixed 13.6 — identical mixed figure to the 307 hp AWD, 0.4 s slower. Restyle 3.5 AT 303 hp RWD 7-speed: 6.0 s, 250 km/h, consumption not measured. Restyle 3.5 AT 303 hp AWD 5-speed: 6.2 s, 250 km/h, consumption not measured.

Pre-restyle 3.5 AT 280 hp RWD: 6.9 s, 224 km/h, mixed 12.6. AWD: 7.1 s, 206 km/h, mixed 13.6. Pre-restyle 4.5 AT RWD: 6.2 s, 238 km/h, consumption not measured.

Highest measured top speed band is 250 km/h (several 4th-generation and restyle rows). Lowest measured top speed is 206 km/h on AWD 3.5 AT 280 hp and 307 hp (restyle and pre-restyle AWD 280). 2.5 AT tops out at 231 km/h. 1st generation 3.0 AT: 0–100 not measured, top speed not measured, all three consumption figures not measured. 2nd generation 4.5 AT: consumption not measured. Restyle 303 hp pair and restyle 4.5 AT AWD: consumption not measured. CO2 is not measured except 4th-generation 3.7 AT AWD at 235 g/km.

Dimensions and weight

Kerb mass, where measured, runs from 1680 kg (4th-generation 2.5 AT) to 1965 kg (restyle 3.5 AT 280 hp AWD). That is 285 kg between the lightest and heaviest listed cars.

Weight per horsepower (kerb / hp), measured rows only: 5.6 AT AWD 1850/408 ≈ 4.53 kg/hp (lowest); 5.6 AT RWD 1873/408 ≈ 4.59; 2nd-generation 4.5 AT 1790/344 ≈ 5.20; 4th-generation 3.7 AT RWD 1715/333 ≈ 5.15; 3.7 AT AWD 1855/333 ≈ 5.57; 2.5 AT 1680/222 ≈ 7.57 kg/hp (highest among measured 4th-generation petrol). Restyle 280 hp AWD 1965/280 ≈ 7.02 kg/hp. 4th-generation 3.0 AT Diesel kerb mass is not measured, so kg/hp is not measured.

AWD add-on mass: 4th-generation 3.7 AT AWD is 140 kg heavier than 3.7 AT RWD (1855 − 1715). Pre-restyle 3.5 AT AWD is 110 kg heavier than RWD (1875 − 1765). Restyle 307 hp AWD is 96 kg heavier than 307 hp RWD (1964 − 1868). Odd row: 4th-generation 5.6 AT RWD is 23 kg heavier than 5.6 AT AWD (1873 vs 1850) despite losing AWD — the catalogue numbers are those, not a theory.

Gross mass: 4th-generation 5.6 AT both drives 2380 kg; 3.7 AT AWD 2360; 2.5 AT 2250; 3.7 AT RWD 2255; 3.0 AT Diesel GVM not measured. 2nd generation 4.5 AT GVM 2190 kg is the lowest measured GVM. Restyle 303 hp pair: GVM not measured on both.

Ground clearance: 1st generation 160 mm; 2nd generation 140 mm; 3rd generation 130 mm; restyle 124 mm (4.5 AT RWD) to 140 mm (4.5 AT AWD); 4th generation 144 mm (3.0 AT) to 149 mm (2.5 AT), with 3.7 AT and 5.6 AT at 145 mm. If winter ruts matter, 4th generation sits 14–25 mm higher than most 3rd-generation rows.

Tank: 85 L (2nd generation 4.5 AT), 80 L (all 4th generation), 76 L (restyle), 75 L (3rd generation), not measured (1st generation). Mixed range arithmetic where both tank and mixed use exist: 3.0 AT Diesel 80 / 7.5 × 100 ≈ 1067 km; 2.5 AT 80 / 9.9 × 100 ≈ 808 km; 3.7 AT RWD ≈ 784 km; 5.6 AT RWD ≈ 667 km; restyle 307 hp RWD 76 / 12.6 × 100 ≈ 603 km.

Wheels: 4th-generation 5.6 AT (both drives) 245/50 R18 and 245/40 R20. 3rd generation all three versions 245/45 R18 and 245/40 R19. All other versions: wheels not measured.

Brakes: 4th-generation 2.5 AT, 3.7 AT AWD and both 5.6 AT — Ventilated disc front and Disc ventilated rear. 4th-generation 3.0 AT and 3.7 AT RWD — Ventilated disc front, Disc rear. 1st generation rear brakes not measured.

Engine placement Front, longitudinal is measured on 4th-generation petrol except 3.0 AT and 3.7 AT RWD (placement not measured) and on restyle/3rd/2nd rows where filled; 1st generation placement not measured.

Reliability and data gaps

This catalogue has no failure rates, service intervals or problem lists. What is missing is listed as not measured: 1st-generation performance and mass; several restyle consumption and GVM cells; Diesel kerb mass; wheels on most versions; CO2 on all but one row. Those gaps are not evidence that the car lacks the parameter.

Which version to choose

Buy 4th-generation (2010–2013) 3.0 AT Diesel RWD if mixed litres matter. It is the only Diesel, the only Turbo, 550 Nm at 1750 rpm, 6.9 s, 250 km/h, 7.5 / 5.9 / 10.3 L/100 km (mixed / highway / city), Euro 5, 80 L tank. Versus 2.5 AT it is 16 hp up, 297 Nm up (550 − 253), 2.3 s quicker, and 2.4 L/100 km less mixed. Versus 3.7 AT RWD it is 95 hp down but 184 Nm up (550 − 366) and 2.7 L/100 km less mixed. Kerb mass not measured.

Buy 4th-generation 5.6 AT RWD if the stopwatch is the criterion. 408 hp, 550 Nm, 5.2 s, 250 km/h, Direct injection (direct), 8 cylinders, 7-speed Automatic. Versus the same 5.6 AT AWD you gain 0.2 s and 0.5 L/100 km mixed and lose AWD; both share 245/50 R18 and 245/40 R20. Versus restyle 4.5 AT RWD (340 hp, 6.2 s) you gain 68 hp and 1.0 s. Versus 2nd-generation 4.5 AT (344 hp, 5.8 s) you gain 64 hp and 0.6 s, and you have mixed consumption measured (12.0) where the older V8 does not.

Buy 4th-generation 3.7 AT RWD if you want V6 petrol without AWD mass. 333 hp, 366 Nm, 6.2 s, 250 km/h, 1715 kg, 10.2 L mixed, Euro 5. Versus 3.7 AT AWD: −140 kg, −0.1 s, −0.7 L mixed, +4 km/h (250 vs 246), and you lose the only CO2 figure (235 g/km on AWD). Versus restyle 3.5 AT 307 hp RWD (6.4 s, 12.6 mixed, 1868 kg): +26 hp, −0.2 s, −2.4 L mixed, −153 kg.

Buy 4th-generation 3.7 AT AWD if traction is the reason to pay in kilograms. 1855 kg, 6.3 s, 10.9 mixed, 235 g/km CO2. Versus 5.6 AT AWD you give up 75 hp and 0.9 s (6.3 vs 5.4) and save 1.6 L/100 km mixed (10.9 vs 12.5).

Buy 4th-generation 2.5 AT only if displacement and kerb mass are the filter. Lightest measured sedan at 1680 kg, 222 hp, 9.2 s, 231 km/h, 9.9 mixed, 149 mm clearance (highest of 4th generation), Euro 4. It is 2.3 s slower than the diesel and 4.0 s slower than 5.6 AT RWD. Specific output 88.9 hp/L is close to the 3.7 AT (90.1), but 7.57 kg/hp is the worst measured ratio in 4th generation.

Buy 3rd generation, restyling (2008–2010) 3.5 AT 303 hp RWD if you want the restyle’s shortest 0–100. 6.0 s, 250 km/h, 7-speed, 1787 kg, 268 Nm. Consumption not measured — do not treat that as “low use”. The 307 hp RWD 7-speed is 0.4 s slower (6.4) but has 363 Nm (+95 Nm) and mixed 12.6 L/100 km measured. The 280 hp AWD restyle is the slow AWD: 7.1 s, 206 km/h, 1965 kg.

Buy restyle or pre-restyle 4.5 AT if you want the 4494 cm³ eight-cylinder that 4th generation dropped. Restyle RWD: 340 hp, 452 Nm, 6.2 s, 238 km/h, 13.7 mixed, 1905 kg, 124 mm clearance (lowest in the model). Restyle AWD: 340 hp, 451 Nm, 5.8 s, 238 km/h, consumption not measured, 140 mm clearance. Pre-restyle RWD: 340 hp, 461 Nm (highest torque of any 4.5 AT), 6.2 s, 238 km/h, 1790 kg, wheels 245/45 R18 and 245/40 R19. 2nd-generation 4.5 AT is the peak of that family on paper: 344 hp (+4 vs later 340), 5.8 s, 85 L tank, 140 mm clearance, 1790 kg — consumption not measured.

Buy 3rd generation (2005–2008) 3.5 AT 280 hp RWD if you want the simpler five-speed V6 sedan with measured wheels. 6.9 s, 224 km/h, 12.6 mixed, 1765 kg. AWD adds 110 kg, 0.2 s, 1.0 L mixed, and cuts top speed to 206 km/h.

Buy 1st generation 3.0 AT only if the Cabrio body is the point. 164 hp, Automatic 4, RWD, 160 mm clearance, Dependent, spring rear axle. Two catalogue rows, same name, same 164 hp, same blanks. 0–100, top speed, torque, mass, tank and consumption are not measured, so this generation cannot be ranked on pace or economy against the sedans.

Arithmetic summary of “what extra capacity buys” in 4th generation RWD petrol: from 2.5 AT to 3.7 AT is +1200 cm³, +111 hp, +113 Nm, −3.0 s (9.2 → 6.2), +0.3 L mixed (9.9 → 10.2), +35 kg. From 3.7 AT RWD to 5.6 AT RWD is +1856 cm³, +75 hp, +184 Nm, −1.0 s (6.2 → 5.2), +1.8 L mixed (10.2 → 12.0), +158 kg. The diesel sits beside that ladder rather than on it: 2993 cm³, 238 hp, 550 Nm, 6.9 s, 7.5 mixed.

If one row has to be named for a mixed-use sedan from this dataset, it is 4th-generation 3.0 AT. If one row has to be named for acceleration, it is 4th-generation 5.6 AT RWD. If one row has to be named for AWD with a full consumption sheet, it is 4th-generation 3.7 AT AWD. Everything older is a choice of V6 3.5 AT flavour (280 / 303 / 307 hp) or 4.5 AT, with more not-measured cells and, on several AWD 3.5 AT rows, a 206 km/h cap.