Fiat 138 A3.000, Engine
| Engine capacity | 1,280 cm³ |
| Maximum power (range), hp | 75 |
| Fuel used | Petrol |
| Fuel consumption, l/100 km | 8.6 |
| Engine type | In-line, 4-cylinder |
| Cylinder diameter (range), mm | 86.4 |
| Piston stroke (range), mm | 55.5 |
| Valve drive | SOHC |
| Number of valves per cylinder (range) | 2 |