In the automotive field, a **straight line** refers to a section of road that does not change direction. This means that the road follows a **single direction** without deviating.

- **Direction**: It is the line, whether straight or curved, that connects two places. In the case of a straight line, this direction is constant and does not vary.

- **Sense**: It refers to the orientation in which one can travel within that direction. A straight line on a road can have **two senses**, allowing vehicles to travel in both opposite directions within the same direction of the road.

Therefore, a straight line in the automotive field is defined by having **one direction and two senses**. This allows vehicles to move in both directions along the same straight line of the road.