A good way to find out what time gas stations open in a neighborhood is to visit HoursOf.com to find out store hours. The site offers this service for all of the United States. It also provides gas station hours for several cities in England, Scotland and Canada.
This site is geared towards finding open stores in the neighborhood. However, it can also show nearby, closed and unlisted places. The browser may require the user to share his location. The site gives two search choices: enter a query or choose a category. This gives a list of open gas stations in the neighborhood within seconds. Since this is the default result, one needs to click other buttons to get information such as closed gas stations, weekly hours and the next open time.