Average Mileage Going Down After Fourth Fill Up?!

yea. Been there. doesnt mean a thing really. It takes a few thousand before the car gets it's best mpg. I have 4K and mine still is all over the place from 35 to 53 depending on all manner of things from weather to how I drive.

Tires have to wear in. engine needs to loosen up a bit too. Your best days are coming. enjoy them in good health.

 

Relax - your sample size is small and the 30 miles on your last tank is not much. Your car is still in its break-in period, mileage improves around 5K. What's your typical drive: city vs HWY; speeds; distance ... etc?
Mileage killers are: short distances as coolant and engine needs to warm-up (less of an issue in warm LA) - check your first 5 minutes MPG to see what I mean; lots of stop (complete stop) and go traffic - try to anticipate stops and coast instead of coming to a complete stop; hills are more of a challenge to gain good MPG; HWY especially high speeds also will yield lower MPG.
Here are some things you may want to consider for starters:
1. raise your tire pressures to 40/38 (front/rear) or even to the max on your tires (stock: 45/43). Fronts should be +2 of rear due to heavier front weight.
2. limit short trips and combine them. On multiple short stops it is better to first drive to the furthest stop then work your way back.
3. select routes that will keep you moving at moderate speeds.

You can find a lot more detail as you read through PC forums (there is one on Fuel Economy).

For now relax; just drive it observe and read to gain additional knowledge.

Best of luck and congrats on your new car.

 

I have an 08 and after reading all of you guys comments about how to improve MPG, I did Improved from 56.1 MPG to 58.7 MPG in city without using AC base on 31 MPH and 50 MPG to 52.5 MPG base on 65 MPH with AC. I've tried everything to improve my MPG. Below is what i have done :
1. Fill gas half of a tank to reduce heavy weight on a car
2. Set temp to 73
3. Tire Pressure 45 PSI
4. Slowly step on gas penal
5. Accelerate to 36 MPH on 40 MPH (IN CITY ONLY)
6. Release gas penal all the way for only 2 second and slowly step on gas penal to keep your speed on 31 MPH.
7. Shut off AC
8. Release gas penal if you see a stop light in RED Color ( This will always save you a lot of gas everytime you do it)

Hope this will give u an idea and hope to get from you guys back to improve more gas MPG

 

Those 30 miles at 30mpg either had a lot of short trips or short steep hills in them.

As you noticed, now that you've added a couple hundred miles which were more "normal" the fuel economy has already jumped back up to 44mpg. It might go up a few more by the end of the tank.