The acceleration of the car can be calculated using the following formula:

```

acceleration = (change in velocity) / (time taken)

```

In this case, the change in velocity is 40 m/s and the time taken is 80 seconds. Substituting these values into the formula, we get:

```

acceleration = (40 m/s) / (80 s) = 0.5 m/s²

```

Therefore, the acceleration of the car is 0.5 m/s².