You are similar to me! I just hit 2500 with my 1.4 turbo (manual) but I started using regular and then I used premium once but did not notice the difference. I ended up switching back and then noticed my car shake a little and wasn't not sure if it was because the difference in gas quality I used. And so I got worried and just stuck to regular and didn't go to premium since. Now that you mention it, I did average more when using premium. I average 20 city and 26 highway on regular. I do not drive at high speeds.My Renegade has about 2500 miles on it, and I've only filled it with premium fuel. At an extra $2 per tank versus regular, I haven't felt the need to try anything but premium. Out of curiosity I may try regular just to see how it performs, but I've been so satisfied with the performance on premium that I haven't changed. I'm averaging about 22-23 MPG in town, and about 27 on the highway at high speeds (75-80 mph).
if you have a 2.4 it does not need premium. It is designed for 87 and anyone who understands how the computer systems on these engines works knows this.Ok let's put this to rest here I own a 2017 renny. I have run two tanks of all three fuels in it. It runs best with premium fuel I live at 5500 ft above sea level under most cercumstances the lower octane should be fine. However being an engine biulder myself with this non turbo multiair engine having a10/10 to 1 compression ratio even though it is a variable valve timed engine I get better performance as well as economy running premium fuel.and as tested same fuel station same batch . The mid fuel returns about 28 mpg. The premium returns about 35 mpg and there was no difference between the low and mid grade other than you can hear pre ignition with the low grade fuel so I say premium for longevity and performance as well as economy.