Break the Cycle
Just as firefighters have been trained in fire suppression to remove one of the three required components (air, fuel and heat), mold works in a similar way with moisture, food and spores. Remove the food: Mold does not grow. Remove the moisture: same result.
The most common food sources for mold in a garage are the paper found on drywall and the wood that holds it all up. Replacing the drywall with new paperless versions or building with steel studs is a great way to limit mold growth in new construction, but it tends to be a costly and involved refit in older homes.
Here, taking away the moisture is a better place to focus your efforts. A simple coat of paint can often be the needed barrier to keep the moisture away from the drywall’s paper. Fixing minor leaking in roofs and siding can also keep the moisture out. When you drive your car into your garage after snow or a rainstorm, most of that moisture will stay in your garage for some time and can potentially add to moisture and mold problems. Drains and proper floor slope can do wonders.