Alfa Romeo 6

Alfa Romeo 6: which version to buy (1979–1988)

The Alfa Romeo 6 in this catalogue is one generation (1979–1988), a Sedan, and four factory versions: 2.0 MT, two petrol 2.5 MT cars (158 hp and 160 hp), and a diesel 2.5 MT (105 hp). There is no later generation to “wait for,” no restyle listed as a separate generation, and no automatic or all-wheel-drive option in the data. The buying question is which of these four drivetrains to take.

The Alfa Romeo 6 in this catalogue is one generation (1979–1988), a Sedan, and four factory versions: 2.0 MT, two petrol 2.5 MT cars (158 hp and 160 hp), and a diesel 2.5 MT (105 hp). There is no later generation to “wait for,” no restyle listed as a separate generation, and no automatic or all-wheel-drive option in the data. The buying question is which of these four drivetrains to take. People searching Alfa Romeo 6C, 6C 2500, GTV 6, Giulia, Giulietta, 159, 690T, or 6 Underground cars are looking at other models; this page is only the Alfa Romeo 6 sedan and the four versions named above.

Specs that actually split the four versions

Shared hardware across all four: 5-speed Manual, RWD, 77-litre tank, 140 mm ground clearance, independent torsion front suspension, dependent spring rear suspension, ventilated disc front brakes, Disc rear brakes. Engine position is not measured on every version. Wheel sizes are not measured. Eco class and CO2 are not measured.

Power per litre and kg per horsepower

Specific output (hp ÷ displacement in litres):

• 2.0 MT: 135 hp / 1.995 L = 67.7 hp/L — highest of the four.
• 2.5 MT 160 hp: 160 / 2.492 = 64.2 hp/L.
• 2.5 MT 158 hp: 158 / 2.492 = 63.4 hp/L.
• 2.5 MT 105 hp diesel: 105 / 2.499 = 42.0 hp/L — 25.7 hp/L below the 2.0 MT.

Kerb weight per horsepower:

• 2.5 MT 160 hp: 1470 / 160 = 9.19 kg/hp — lightest load per horsepower.
• 2.5 MT 158 hp: 1470 / 158 = 9.30 kg/hp (0.11 kg/hp heavier per hp than the 160 hp car).
• 2.0 MT: 1470 / 135 = 10.89 kg/hp (1.70 kg/hp more than the 160 hp 2.5 MT).
• 2.5 MT 105 hp diesel: 1580 / 105 = 15.05 kg/hp — 5.86 kg/hp more than the 160 hp petrol 2.5 MT, and 110 kg more kerb weight than the three petrol cars (1580 vs 1470).

Torque per litre: 2.5 MT 160 hp has 219 / 2.492 = 87.9 Nm/L; 2.5 MT 158 hp 86.3 Nm/L; 2.0 MT 88.7 Nm/L; diesel 2.5 MT 82.4 Nm/L. The 2.0’s torque density is the highest; its absolute torque (177 Nm) is still 38 Nm below the 158 hp 2.5 MT and 42 Nm below the 160 hp 2.5 MT.

Performance and economy: measured vs not measured

0–100 km/h

• 2.5 MT 158 hp: 9.5 s — fastest measured.
• 2.5 MT 160 hp: 10.5 s — 1.0 s slower than the 158 hp car despite +2 hp and +4 Nm.
• 2.0 MT: not measured.
• 2.5 MT 105 hp diesel: not measured.

Top speed

• 2.5 MT 160 hp: 200 km/h — highest.
• 2.5 MT 158 hp: 195 km/h (−5 km/h vs 160 hp).
• 2.0 MT: 180 km/h (−20 vs 160 hp, −15 vs 158 hp).
• 2.5 MT 105 hp diesel: 170 km/h (−30 vs 160 hp).

Fuel use (L/100 km) — city / highway / mixed:

• 2.5 MT 158 hp: 17.9 / 9 / 11.3 — the only petrol with a full set.
• 2.5 MT 105 hp diesel: 10.2 / 7 / 9.4.
• 2.0 MT: city not measured, highway not measured, mixed not measured.
• 2.5 MT 160 hp: city not measured, highway not measured, mixed not measured.

On the two versions that were measured, the diesel uses 7.7 L/100 km less in the city (10.2 vs 17.9), 2 L/100 km less on the highway (7 vs 9), and 1.9 L/100 km less mixed (9.4 vs 11.3). With the same 77-litre tank, mixed range arithmetic is 77 / 11.3 × 100 ≈ 681 km for the 158 hp 2.5 MT versus 77 / 9.4 × 100 ≈ 819 km for the diesel 2.5 MT (+138 km). Highway: 77 / 9 × 100 ≈ 856 km vs 77 / 7 × 100 ≈ 1100 km. City: 77 / 17.9 × 100 ≈ 430 km vs 77 / 10.2 × 100 ≈ 755 km. Those ranges are not factory figures; they are tank ÷ consumption from the same table.

Dimensions and weight (what does not change)

Ground clearance is 140 mm on all four. Tank is 77 L on all four. Wheel size is not measured on all four.

Kerb weight: 1470 kg for 2.0 MT, 2.5 MT 158 hp, and 2.5 MT 160 hp; 1580 kg for diesel 2.5 MT. Gross weight is 1830 kg on both petrol 2.5 MT cars and not measured on 2.0 MT and the diesel 2.5 MT. Payload on the two cars where both masses exist: 1830 − 1470 = 360 kg. Compression: 10 on all three petrol versions; 22 on the diesel. Bore × stroke: 2.0 MT 84 × 90; both petrol 2.5 MT 88 × 68.3; diesel 92 × 94.

The two 2.5 MT petrol cars: 158 hp vs 160 hp

Same name, same 2492 cc, same 6 cylinders, V-shaped, 2 valves per cylinder, No boost, 5-speed Manual, RWD, 1470 kg, 1830 kg gross, 77 L, 140 mm. Differences that matter for a purchase:

1. Induction: 158 hp uses Distributed injection (multi-point); 160 hp uses Carburetor. 2. Peak rpm: 158 hp peaks at 5600 rpm; 160 hp at 5800 rpm (+200 rpm). Torque peak is 4000 rpm on both. 3. Outputs: 160 hp is +2 hp (+1.3%) and +4 Nm (+1.9%). 4. 0–100: 158 hp is 1.0 s quicker (9.5 vs 10.5). 5. Top speed: 160 hp is 5 km/h faster (200 vs 195). 6. Economy: measured only on the 158 hp car (17.9 / 9 / 11.3). The 160 hp car’s consumption is not measured — do not treat it as “unknown because it does not exist”; it was not recorded in this dataset.

If the goal is the shortest measured sprint, the 158 hp 2.5 MT wins on the only 0–100 pair we have. If the goal is the highest listed top speed, the 160 hp 2.5 MT wins by 5 km/h. The extra 2 hp does not buy a faster 0–100 in these numbers.

2.0 MT versus either petrol 2.5 MT

Same kerb weight (1470 kg), same gearbox, drive, tank, clearance, suspension, brakes. You give up 497 cc versus the 2492 petrol sixes (1995 vs 2492), 2 cylinders (4 Inline vs 6 V-shaped), and 23–25 hp (135 vs 158–160). Torque is 177 Nm versus 215–219 (−38 to −42 Nm). Top speed is 180 versus 195–200 (−15 to −20 km/h). Fuel system is Carburetor, same family as the 160 hp 2.5 MT, not the injected 158 hp car. 0–100 and all three consumption figures for 2.0 MT are not measured, so you cannot rank it against 9.5 s or 11.3 L/100 km with a factory number.

What the 2.0 does win: highest hp/L (67.7) and highest Nm/L (88.7) of the four. It is the lightest-cylinder petrol, not the lightest car — mass is identical to the petrol 2.5s.

Diesel 2.5 MT (105 hp) versus the petrol three

Displacement is 2499 vs 2492 on the petrol sixes (+7 cc) and +504 cc versus 2.0 MT. Layout is 4 Inline with Turbo, not 6 V-shaped and not naturally aspirated. Peak power is the lowest (105 hp at 4300 rpm — 1300–1500 rpm earlier than the petrol peaks). Peak torque is 206 Nm at 2400 rpm, 1600 rpm earlier than the petrol 2.5 MT cars (4000) and 2100 rpm earlier than 2.0 MT (4500). Versus 158 hp petrol: −53 hp, −9 Nm, +110 kg, −25 km/h top speed (170 vs 195). Versus 160 hp: −55 hp, −13 Nm, −30 km/h. Versus 2.0 MT: −30 hp, +29 Nm, +110 kg, −10 km/h.

The diesel is the only Turbo in the table and the only Diesel fuel. Mixed consumption, where both exist, is 1.9 L/100 km better than the 158 hp petrol. City gap is 7.7 L/100 km. That is the economy case. The performance case is against it on every measured speed figure. 0–100 is not measured, so a “slow diesel sprint” is not a number here — only top speed 170 km/h is.

Which version to choose

Choose 2.5 MT (158 hp) if you want the only petrol with a complete performance-and-mpg sheet and the fastest measured 0–100 (9.5 s). It is also the only Distributed injection (multi-point) petrol. Same 1470 kg as the other petrols, 195 km/h, 215 Nm, 11.3 mixed. For a catalogue buyer ranking “which 2.5 to live with using published figures,” this is the one that is fully populated.

Choose 2.5 MT (160 hp) if the 200 km/h top speed and 219 Nm / 160 hp peaks matter more than the 1.0 s slower 0–100. You accept Carburetor instead of Distributed injection (multi-point), and you accept that city, highway, and mixed consumption are not measured. Arithmetic on power is tiny (+2 hp, +4 Nm); arithmetic on sprint time goes the other way.

Choose 2.0 MT if you want the 4 Inline Gasoline at 1995 cc, 135 hp, 67.7 hp/L, 1470 kg, 180 km/h, Carburetor, No boost. You do not get a 0–100 or mpg figure in this dataset. You do not save weight versus the petrol 2.5s. You do save cylinders and 497 cc. Fuel is 95, same as the other petrols.

Choose 2.5 MT (105 hp) if mixed 9.4 L/100 km, city 10.2, highway 7, torque at 2400 rpm, Turbo, Diesel, and the ~138 km extra mixed tank arithmetic versus the 158 hp petrol matter more than 105 hp, 15.05 kg/hp, 1580 kg, and 170 km/h. Gross weight is not measured on this version (and not measured on 2.0 MT).

There is only 1 generation (1979–1988), so there is no “later chassis” trade: suspension, brakes, drive, tank, and clearance do not change between versions in the data. The generation did not add a second body; it is Sedan only. Reliability, prices, and “for sale” stock are not in the data — not measured here — and are not used to rank the four.

Short ranking on measured speed: 158 hp 2.5 MT (9.5 s, 195 km/h) ahead of 160 hp 2.5 MT on sprint, behind it on top speed; 2.0 MT 180 km/h with 0–100 not measured; diesel 2.5 MT 170 km/h with 0–100 not measured. Short ranking on measured mixed mpg: diesel 2.5 MT 9.4, then 158 hp 2.5 MT 11.3; the other two not measured. Buy the version whose filled columns match the job; empty columns stay “not measured,” not “better” or “worse.”