Pontiac G8

Which Pontiac G8 version to buy

The Pontiac G8 was built as 1 generation from 2007-01-01 to 2009-12-31, body Sedan, 8 versions, all Gasoline, all Front, longitudinal, all RWD, all No boost, all Distributed injection (multi-point), all Independent, spring front and rear, all Disc brakes front and rear, all with a 73 L tank.

The Pontiac G8 was built as 1 generation from 2007-01-01 to 2009-12-31, body Sedan, 8 versions, all Gasoline, all Front, longitudinal, all RWD, all No boost, all Distributed injection (multi-point), all Independent, spring front and rear, all Disc brakes front and rear, all with a 73 L tank. There is no second generation to pick, so the choice is engine, gearbox, and the two power ratings that share the same names.

Spread in the data: power 256–415 hp (188–305 kW), torque 336–549 Nm, displacement 3564–6162 cc, kerb 1765–1815 kg. The only 0–100 km/h figures that exist are 5.3 s on 6.0 AT 361 hp and 4.5 s on 6.2 AT 415 hp. Fuel use, top speed, CO2, eco class, gross weight, and wheel sizes are not measured on every version. Ground clearance is 110 mm where it is measured and not measured on three versions.

Generations: what actually changed

1 generation (2007-01-01–2009-12-31). One body (Sedan), eight versions, no restyle as a separate generation. All eight sit in the same years. What “changed” is not a later generation but the engine and gearbox mix: two 3.6 AT cars at 256 hp and 264 hp, four 6.0 cars at 361 hp and 367 hp with Automatic or Manual, and two 6.2 cars at 415 hp with Automatic or Manual.

Specs: eight versions side by side

Valves per cylinder: not measured on 3.6 AT 256 hp, 4 on 3.6 AT 264 hp, 2 on all four 6.0 versions, not measured on both 6.2 versions. Compression: not measured / 10.2 on the two 3.6 AT cars; 10.9 on both 361 hp 6.0 cars; 10.4 on both 367 hp 6.0 cars; not measured on both 6.2 cars. Bore × stroke: not measured on 3.6 AT 256 hp; 94 × 85.6 on 3.6 AT 264 hp; 101.6 × 92 on all four 6.0 cars; not measured on both 6.2 cars.

Engine: power per litre and what the extra displacement buys

3.6 AT 256 hp: 256 / 3.564 = 71.8 hp/L. 3.6 AT 264 hp: 264 / 3.564 = 74.1 hp/L — the densest specific output in the table, +2.3 hp/L over the other 3.6 AT.

6.0 MT and 6.0 AT at 361 hp: 361 / 5.967 = 60.5 hp/L. 6.0 AT and 6.0 MT at 367 hp: 367 / 5.967 = 61.5 hp/L. The 6.0 cars make more total power because they have +2403 cc versus 3564, not because they are more efficient per litre: they sit 10.5–13.6 hp/L below the 264 hp 3.6 AT.

6.2 AT and 6.2 MT: 415 / 6.162 = 67.3 hp/L. Versus 3.6 AT 264 hp that is −6.8 hp/L; versus 6.0 367 hp that is +5.8 hp/L. The 6.2 step from 5967 to 6162 cc is only +195 cc (+3.3% displacement) for +48 hp over 367 (+13.1%) and +54 hp over 361 (+15.0%).

Torque per litre: 3.6 AT 256 hp 336 / 3.564 = 94.3 Nm/L; 3.6 AT 264 hp 339 / 3.564 = 95.1 Nm/L; 6.0 361 hp 522 / 5.967 = 87.5 Nm/L; 6.0 367 hp 530 / 5.967 = 88.8 Nm/L; 6.2 549 / 6.162 = 89.1 Nm/L. The 3.6 AT pair is the torque-dense choice; the 6.0 and 6.2 cars win on absolute Nm.

Peak rpm where measured: the 3.6 AT pair peaks at 6300 rpm for power; 6.0 361 hp at 5200; 6.0 367 hp at 5700; 6.2 power rpm is not measured. Torque peaks: 2100 on 3.6 AT 256 hp (earliest in the set), 3200 on 3.6 AT 264 hp, 4000 on 361 hp 6.0, 4400 on 367 hp 6.0, not measured on 6.2.

Performance and economy (mpg): what is measured

0–100 km/h: 6.0 AT 361 hp 5.3 s; 6.2 AT 4.5 s — 0.8 s quicker. 3.6 AT (both), 6.0 MT (both), 6.0 AT 367 hp, and 6.2 MT are not measured. Do not treat a missing 0–100 as “slow”: it is absent.

Top speed: not measured on all eight.

City / highway / combined consumption: not measured on all eight. There is no mpg ranking in this dataset. Fuel grade is 92 on 3.6 AT 256 hp, both 361 hp 6.0 cars, and both 6.2 cars; not measured on 3.6 AT 264 hp and both 367 hp 6.0 cars.

CO2 and eco class: not measured on all eight.

Dimensions, weight, tank

Kerb weight: 1765 kg (3.6 AT 264 hp, lightest), 1790 kg (3.6 AT 256 hp, 6.0 MT 361 hp, 6.0 AT 361 hp, 6.2 AT, 6.2 MT), 1800 kg (6.0 MT 367 hp), 1815 kg (6.0 AT 367 hp, heaviest). Gross weight: not measured on all eight. Ground clearance: 110 mm on 3.6 AT 256 hp, both 361 hp 6.0 cars, and both 6.2 cars; not measured on 3.6 AT 264 hp and both 367 hp 6.0 cars. Tank: 73 L on all eight. Wheel sizes: not measured on all eight.

Weight per horsepower (kg/hp):

• 3.6 AT 256 hp: 1790 / 256 = 6.99
• 3.6 AT 264 hp: 1765 / 264 = 6.69 (best among the six-cylinder pair, 0.30 kg/hp lighter than the other 3.6 AT)
• 6.0 MT 361 hp and 6.0 AT 361 hp: 1790 / 361 = 4.96
• 6.0 AT 367 hp: 1815 / 367 = 4.95
• 6.0 MT 367 hp: 1800 / 367 = 4.90 (best 6.0)
• 6.2 AT and 6.2 MT: 1790 / 415 = 4.31 (best in the model, 2.68 kg/hp less than 3.6 AT 256 hp)

The 6.0 AT 367 hp is +25 kg versus 1790 kg and +15 kg versus 6.0 MT 367 hp. Extra mass almost cancels the +6 hp versus 361 hp: 4.95 vs 4.96 kg/hp.

Which version to choose

If the goal is the lowest kerb and the strongest 3.6-litre numbers: 3.6 AT (264 hp). Versus 3.6 AT 256 hp: +8 hp (+3.1%), +6 kW, +3 Nm, same 3564 cc, same Automatic 5 and RWD. Kerb 1765 vs 1790 = −25 kg. Specific output 74.1 vs 71.8 hp/L. This 3.6 AT also has the only 3.6 compression (10.2), bore × stroke (94 × 85.6), and 4 valves per cylinder in the data. Trade-off: fuel grade and clearance are not measured; the 256 hp 3.6 AT lists 92 and 110 mm. Torque peak is 3200 rpm versus 2100 on the 256 hp car — more peak Nm later in the rev range.

If the goal is the documented 3.6 with 92 fuel and 110 mm clearance: 3.6 AT (256 hp). It is the weaker, heavier 3.6 AT (256 vs 264 hp, 1790 vs 1765 kg) but it is the 3.6 AT that actually records 92, 110 mm, and the earliest torque peak (336 Nm @ 2100). Valves, compression, and bore × stroke are not measured.

If the goal is a 6.0 with a timed 0–100: 6.0 AT (361 hp). It is the only 6.0 with 0–100: 5.3 s. Versus 3.6 AT 264 hp: +97 hp (+36.7%), +183 Nm (+54.0%), +2403 cc, gearbox Automatic 6 instead of 5, kerb 1790 vs 1765 = +25 kg. Versus 6.0 MT 361 hp: same 361 hp, 522 Nm, 5967 cc, 10.9 compression, 101.6 × 92, 92 fuel, 1790 kg, 110 mm — the difference is Automatic 6 versus Manual 6, and only the Automatic has 5.3 s (the Manual 0–100 is not measured).

If the goal is a 6.0 Manual at the same 361 hp: 6.0 MT (361 hp). Same engine numbers as 6.0 AT 361 hp. You give up the only 6.0 sprint figure. Compression 10.9 is the highest in the whole G8 set (the 367 hp 6.0 pair is 10.4; 3.6 AT 264 hp is 10.2; others not measured).

If the goal is the 367 hp 6.0 Automatic: 6.0 AT (367 hp). Versus 6.0 AT 361 hp: +6 hp (+1.7%), +8 Nm, power peak 5700 vs 5200, torque peak 4400 vs 4000, compression 10.4 vs 10.9, kerb 1815 vs 1790 = +25 kg. 0–100, fuel, and clearance are not measured on this 6.0 AT; they are measured on the 361 hp 6.0 AT. The extra 6 hp does not improve kg/hp (4.95 vs 4.96). Buy this 6.0 AT only if 367 hp / 530 Nm / 270 kW is the requirement; it is not the quicker-on-paper 6.0 AT.

If the goal is the lightest 367 hp car: 6.0 MT (367 hp). Same 367 hp / 530 Nm as 6.0 AT 367 hp, Manual 6, kerb 1800 vs 1815 = −15 kg, 4.90 vs 4.95 kg/hp. Versus 6.0 MT 361 hp: +6 hp, +8 Nm, +10 kg (1800 vs 1790), compression 10.4 vs 10.9. Fuel, clearance, 0–100: not measured.

If the goal is the least kg/hp and the only sub-5 s 0–100: 6.2 AT. 415 hp, 305 kW, 549 Nm, 6162 cc, Automatic 6, RWD, kerb 1790 kg, tank 73 L, clearance 110 mm, fuel 92, 0–100 4.5 s. Versus 6.0 AT 361 hp: +54 hp (+15.0%), +27 Nm (+5.2%), +195 cc, same 1790 kg and 110 mm, 0.8 s quicker (4.5 vs 5.3). Versus 6.0 AT 367 hp: +48 hp, +19 Nm, −25 kg, and a measured sprint the 367 hp 6.0 AT does not have. Power and torque rpm, valves, compression, bore × stroke: not measured. This is the version the numbers point to if “fastest measured Pontiac G8” is the filter.

If the goal is 415 hp with a Manual: 6.2 MT. Same 415 hp, 549 Nm, 6162 cc, 1790 kg, 110 mm, 92, 73 L as 6.2 AT. Gearbox Manual 6. 0–100 not measured — you cannot claim it matches the 4.5 s of 6.2 AT. Same 4.31 kg/hp as 6.2 AT.

Problems and reliability (what the numbers do and do not say)

This dataset has no failure rates, recall lists, or service intervals. What it does show as choice constraints:

• Same name, different cars: two 3.6 AT, two 6.0 AT, two 6.0 MT. Always split by hp.
• Boost is No on all eight — no turbo/supercharger split.
• Drive is RWD on all eight — no AWD option in the data.
• Body is Sedan only.
• Economy, top speed, CO2, wheels, and gross weight cannot be used to rank versions: they are not measured.
• Clearance 110 mm is the only measured figure; three versions leave it not measured, so they cannot be called “higher” or “lower.”

Short buy map

There is one generation, so “which generation” is not a G8 question. The real split is 3.6 AT versus 6.0 versus 6.2, then Automatic versus Manual, then the duplicate names by hp. The data’s only timed pair is 6.0 AT 361 hp at 5.3 s and 6.2 AT at 4.5 s; everything else in the performance column is not measured.