This will differ from tram to tram. According to this source, new Hyundai trams used in Warsaw have a power consumption of 15 Wh per passenger-kilometer, and electric cars 30 Wh, which isn’t true according to a quick google-there is no car that’s this efficient, unless it was packed to the brim. More importantly trams are way more likely to have a lot of people on board as opposed to cars, which most of the time carry only the driver.