My 07 si cpe gets about 300 per tank and I drive it semi hard!!

 

My other vehicle is an '03 Element EX AWD w/auto. My driving is probably 65/35 highway/city. I put a K&N air filter and a cat-back exhaust on the Element hoping to raise the MPG. That vehicle averages 22mpg, which I feel is poor for a 4 cylinder.[:'(]
My '07 Civic EX w/5 speed is much better.Though it varies upon my driving, I am averaging 34.5 mpg.I do put 34 lbs of air in the tires instead of 32 and check them at every fill-up. I wish I was getting better mpg, but it is a vast improvment over the Element...
I've heard that the EPA estimates for '08 have changed, making them more realistic. The Civic (I believe) is now rated at 34 mpg highway instead of 38...

 

Well, here's an update... I recently got my first oil change, and my MPGs improved. My MPGs before the oil changed averaged around 33MPGs with a few highs at 35 MPGs and lows at 30MPGs.

From the time of the oil change, I've only had to fill up once, and I got 37.142MPGs. I mostly highway, but drive a decent amount of city driving also. I thought that it would be worse because that tank I did more city driving than usual, and I've been having the heater on with a/c on for most of the time also.

The next tank I'm going to try to reduce the use of my heater and see if that makes a huge difference.

 

No. Using heater does not affect your MPG because it uses the heat that is generated by the engine to heat the interior of your car and that is why it takes time for the heater to heat up. Don’t bother with the heater and MPG concept. A/C has a compressor and when it is turned on, that takes a little bit of power from the engine to turn the compressor. Heater does not turn on any type of compressor or uses engine power, just the heat from the engine heating up the coolant.

 

But the thing is, I usually have the a/c on while the heater is on with the vents closed because if I don't the windows would fog every 2 minutes... If I'm kinda cold, then I'd open the vents, while the heat is on, so it doesn't take any power for the a/c to turn on. But my last tank I kept it on heater and a/c full blast vents closed.

 

LuV2SkRaTcH: Once the temp gets below about 40F degrees or so, the A/C no longer turns on. Even when the light is on it is not engaged. The refrigerant can get no lower than about 50F degrees so it is useless to havethe A/Crun at lower temps.

Here aremy mileage stats since my last post in this thread. Notice the last two entries. The weather has become wintery in northern Illinois and the mileage is falling off as a result. The engine now requires more gas at startup and the car does not roll/coast nearly as well in colder weather. I currently do mostly city driving with about 25% highway.

367 miles on 10.361 gallons for 35.4 MPG
377 miles on 9.957 gallons for 37.9 MPG
390 miles on 10.550 gallons for 37.0 MPG
315 miles on 9.378 gallons for 33.6 MPG
337 miles on10.632 gallons for 31.7 MPG

 

The a/c has to be doing something if it clears my fogged windows in a few seconds... although, the outside temp doesn't usually get golder than 40 degrees, it's been as low as 35 degrees. Kinda weird for my area. But the a/c has to be doing something... when my windows fog up because my heater is on, I switch on the AC and it slowly goes away unless I turn down the heat (to prevent the window from cracking because of the hear)... then set it to the defroster setting...

 

I have an 07 LX coupe, 5 spd, manual, the first milage I got on the first tank was under 25mpg, but I don't think they actully filled the car like I do, I put in as much fuel as it will hold, since then I have been getting the same amout of fuel, in every tank, for the test purpose, and since then I have 1900 miles on my car, I have been getting between 35 and 39Mpg, I do short shift, and avoid gears if I can, there is no reason to run through every gear, unless your climbing a hill.

Mostly I run first out hit 2nd, and then almost immediatly hit 5th, where I can, all my mileage is in town, and only if its unbareably hot do I use the air, my car stands inside the garage,most of the time so it's never that hot when I get in, so I rarely use air, I wouldrather have the windows down, on a beautiful hot day.

 

I have 3200 miles on my 2007 Civc Si sedan and checked my MPG. Bad time to do it because we had 2 ice

storms and a couple snow storms here north of Chicago, so I had to warm it up several times. I got 18.5 MPG

all city miles. 30-45 mph. I don't baby my car, I drive it pretty hard, but not all the time. Its an Si so rpm's

are needed for power.

 

I would be expecting a factory recall soon because obviously something's not quite right with the cars. There might be an issue with the IAT, MAP, or O2 sensors, or even a bad lot of EGR valves. Switching to a lighter weight synthetic oil might help as well.

I mean, even my rescued and repaired '95 VX (bought it with a warped head and blown headgasket) is now getting a solid 34mpg - and I drive it like I stole it since I've had it. The only mod I've done to it is switched to a K&N-style cone filter.

Good luck with whatever choice you come up with.