2009 Hyundai Sonata, V-6.
On start up sometimes smell a vinegar odor. Dissipates fairly quickly. Any thoughts on cause?
Could be mold in the AC vents and ducts.
Are you sure it’s vinegar and not ammonia? If it’s ammonia, look for nesting rodents in the ventilation system. In any event, check around your cabin air filter if your car has one.