I have a 2002 Z24 with the 2.4, i have been getting terrible city mileage. I get around 14-16 mpg just driving normally, no hard accelerations or "hot dogging" as my mom calls it. You guys have any clue as to what i can do/fix to increase this. I've read that normal mpg city is around 20 or higher. I'm 16 and this is my first car so I'm not really sure as to what it could be. Also i checked for vacuum leaks but all i found was a few loose hose clamps. The car has 128k on it and the previous owner was my uncle who was religious with regular maintenance so i have excluded those issues. Thanks!

If the car has not shown a check engine light,something clearly is not correct.Even if maintenance is done accordingly things can fail even when new parts go bad sooner/than later.You can do the cheaper updates like plugs,fuel filter and air filter.Next is get the injectors flushed unless done recent say less than 10k.If the oxygen sensor(s) were going they generally pop a code.I can't recommend anything more other than basic checks like you mentioned vacuum lines broken at the moment.Make sure the tire's are at proper pressure I choose 32psi for my ride's however ever car has different specs based on tire size!I would pull one or two plugs to make sure the car is not running (rich) meaning a fuel issue related component is wearing down.Just some idea's even though I am a 1st gen guy I own newer rides's that are just as complicated or similar to a 3rd gen in general.Granted I may have left off some key thing's not mentioned and may other's add/correct me if I got things out of sort's.

I checked the plugs (which are only 2k miles old) and they look fine. I compared them to my moms Honda and they look almost identical. The air filter was also replaced 2k miles ago along with the oil, both of those items look completely normal...almost new. My tires were at the correct pressure all around. The injectors though, i'm not really sure if that would cause the engine to use more fuel if they were clogged. ill run a thing of injector cleaner when i get the chance but i doubt that would do anything. it may have just been a bad batch of gas honestly. Anyways, when i removed the ignition system to get to the plugs, i noticed a bunch of dirt/debris/oil around and on the spark plug boot. i'm not sure if thats worth mentioning or not. now i'm considering replacing the coils because those have never been replaced along with the fuel filter.

Is your car running rich? You could get a odd reader and check out the fuel trim levels. MY car was running rich and had two injectors that wouldn't close and would leak fuel, but i was also getting check engine codes. i used a method like this to test https://www.youtube.com/watch?v=rUUgR94drxg