Vehicle Heading
Which direction creatures are facing on a grid is generally irrelevant in Starfinder, but vehicles aren’t as nimble, so you need to monitor a vehicle’s heading each time it moves. If you’re using miniatures, rotate the vehicle’s miniature to face the correct direction whenever its heading changes. The vehicle has to face toward one of the edges of its space, not toward a corner.
When a vehicle has to move at its current heading (such as during a race action or when uncontrolled), it has to move in a straight line. This line is measured from the center of the vehicle on its front edge, and it can be straight ahead or at an angle, as shown in the diagram on page 279. The angle can’t be greater than 45 degrees diagonally from the heading.
Source
Core Rulebook pg. 278