Final answer:
Tim could significantly reduce his car-related expenses after moving to a city with excellent public transportation, as he could rely on this system instead of maintaining a personal vehicle.
Step-by-step explanation:
If Tim is single with no dependents and is looking to increase his savings by reducing or eliminating a category of expenses after moving to a city with excellent public transportation, the category he could significantly reduce would be A) Car-related expenses (fuel, insurance, maintenance).
In a city with good public transport, Tim could rely on this system rather than maintaining a personal vehicle, thereby saving on frequent costs associated with car ownership. This could lead to substantial savings since car ownership entails a multitude of recurring expenses like fuel, insurance, and routine maintenance, which together can amount to a significant portion of one's budget.