Getting a ride to work every day from a coworker who lives nearby can feel like a simple favor, especially when they are already heading in the same direction. But when those rides become a regular part of the workweek, the question of whether the passenger should contribute toward gas naturally comes up.
There is generally no automatic obligation to pay unless the two coworkers agreed on it beforehand. If the driver would make essentially the same trip regardless, taking along a nearby coworker may add very little to the actual fuel cost. Still, the driver is providing something valuable by making transportation easier for the passenger.
Offering to contribute is often the fairest approach. That does not necessarily mean paying half of every tank of gas. The passenger could offer a reasonable weekly amount, occasionally pay for a fill-up, buy the driver coffee or lunch, or find another arrangement that both people consider fair.
The situation changes if picking up the passenger requires a significant detour or additional driving. In that case, contributing toward fuel becomes more reasonable because the driver is spending additional money and time specifically to provide the ride. The best solution is simply to discuss expectations rather than allowing either person to quietly become frustrated.
So, you are not automatically obligated to chip in for gas simply because a coworker drives you to work, but if the rides happen every day, offering something in return is a considerate gesture. Whether the driver accepts it is ultimately up to them, and a simple conversation can prevent a friendly favor from becoming an uncomfortable issue.