Hey All,

I've owned my 2003 Civic Si for almost 2 years now and I'm noticing that i'm driving on the highway more, and i'm getting poor gas mileage (most i've ever gotten was 250 miles off a tank).

When i drive my gf's Jetta 1.8T, i can consistently get 300mpg to a tank (also 10 gallons of gas), even driving 75 on the highway.

Anyway, what is everyone else getting - Si, RSX, or RSX Type S?? Thanks!

 

The best i have gotten so far is 304 miles to the tank (05 RSX-S), that was a mix of highway and stop go traffic. I sit in traffic almost everyday going to and from work, so the best i got doing that is somewhere around 260 or so. I tought it would get better milage also, guess not.

 

High octane = super fuel economy, just in case you're using regular unleaded.

And I know people talk about this often enough, but I have noticed a huge difference, because I can go from Atlanta to Savannah on one tank of Super, whereas with Regular I had to stop and fuel up agian before I arrived.

 

I only use 93 octane, the car only has 945 miles on it, so i guess it just needs to break in.

 

i have a 04 sir. most i got out of one tank of 89 octane gas was 330 km. i used supreme gas and got even worse numbers, 280km to the tank. maybe car is too new, just did the first oil change today, car has 7800km. i hope gas mileage goes up, i drive mostly city so maybe that's why im' not getting much either.

 

These cars can have a huge variation. On the low end I've gotten as low as 17 mpg -- short trips on a cold engine, stoplight to stoplight, lots of high revving. However, on the high end I've gotten up to 34.5 mpg which was all open interstate driving with cruise control. (All on 93 octane.)

 

Honda lists 26/31 mpg, i haven't been able to get 26 on the highway let alone the city! I put a K&N filter on and that didn't seem to have an effect on economy. 75mph = ~4000RPM's, everyone says to drive at 3000RPM's which is ~60mph and economy will improve. Anyway, i expected better mileage out of a civic! Last tank was 220 miles. Any others?

 

Well, all I can suggest are the fairly obvious things:

Make sure your air filter is clean.
Make sure your tires are properly inflated.
Make sure your alignment is within spec.
Use 93+ octane; try different brands.
Use synthetic oil.
Try a fuel system cleaner (such as Chevron's).

But really the best suggestion with these cars is to change your driving style. These cars are a blast to rev high, but if you're wanting the best fuel economy that's the first thing you want to avoid. Some owners swear they can actually see the fuel gauge drop when they rev to redline.

 

you reccommend 93 octane for the 160hp Si engine? i know the lucky RSX-S owners have to use it, i've always used regular.
i have to filll up tonight i'll give that a shot and try to keep my foot out of the floorboards =D

 

A higher octane gas is definitely something to try -- and if you always buy the same brand of gas you might want to try a different brand for a while to see if it makes any difference. But yeah, taking it easy on the accelerator should make the biggest difference in fuel economy. I don't normally worry too much about low gas mileage (I just filled up yesterday and calculated 19 mpg) since I have gotten really good gas mileage on those rare times when I'm taking it easy.