Every time I fill up the tank, it used to give me around 375 miles, but not anymore. 
Note: Kia Soul 2020
Lower mileage could be due to aggressive driving, low tire pressure, or engine issues. Check your tire pressure, air filters, and consider getting your car serviced to see if that helps improve your mileage.
A few things could be causing this: driving habits (like more aggressive acceleration), tire pressure (underinflated tires can hurt fuel economy), or maybe even a clogged air filter.
Also, check for any warning lights on the dashboard. If you’ve recently changed driving conditions or habits, pay attention to those.
If the problem persists, a visit to your mechanic for a checkup might be in order.
Are you only driving in the city? Stop and go traffic will suck the gas no matter what car it is.
Do you know when the last time was that the spark plugs were changed or the fuel injectors were cleaned? Every “new-to-me” car I get I always do these things first;;
A) replace the spark plugs with mid tier plugs, B) clean the throttle body C) replace air filters D) drive it Until I have a quarter tank of gas left, pour in a can of sea foam, drive it till the empty lights comes on then fill up. This will push a concentration of cleaner through the system E) change the oil.
The plugs may not need it,the oil may be fine, it may be overkill, but at least you know you did it at the start and have a baseline for whatever problems come up next. And you start to familiarize yourself with the car. And it’s an excuse to have a couple beers in the driveway on a Saturday afternoon.
If a vehicle has a fuel consumption issue, examining the fuel trim on a scan tool can provide diagnostic information about whether a rich condition occurs or a “false lean” signal is being issued. A minor exhaust leak before an oxygen sensor might cause a misleading lean signal that consumes fuel. First things first. Calculate genuine highway fuel economy to obtain hard statistics with the fewest variables possible.