Most fuel efficient speed for Civic HX?
 

I have been driving 55 MPH whenever possible for years. A while after purchasing Chorizo, I read that lean burn did not come on until 2,600 RPM, which would require driving sixty-five miles an hour, which is the speed limit on most highways and freeways around here. Of course, the only way to accurately know my instantaneous fuel economy is the MPGuino, which is complicated, because you need to build your own, and then chop up your wiring. I average 45 MPG, I do not drive as much as many people, and I am unemployed until I complete my internship, obtain my license, start a job, and then wait a couple of weeks, so I am not sure on the ROI.

I drove to Mom's for Father's Day, went to bed early before driving back, woke up in the middle of the night, could not get back to sleep, so instead of waking up early and driving before it was too warm for the limited ventilation with my grill block\air dam, I just went ahead and drove through elk country while it was still dark, but instead of driving my customary 55 MPH, I drove forty-five.

Was I going to get better fuel economy or worse? After ten or fifteen miles, I pulled up Torque and it said that I was getting 47 MPG on seemingly level ground, which was disappointing. Once the sun was up, I sped up to 55 MPH and checked again; it said that I was getting 70 MPG, also on what appeared to be flat ground. I know that there are many factors, the car could have been more warmed up, it was probably a lower elevation and slightly warmer, etc., so I am asking if anyone has better information.

Thank you very much! :)

Have you tried driving in fourth gear? That should give you the revs you need for lean burn at lower speed. Maybe the lower aero load makes up for the extra revs.

With my HX, I drove 60-65 and averaged about 45 as well.

Elevation changes kick my HX (slambo!) out of lean burn, real fast. I've been looking for a seriously long stretch of flat 55-65 MPH road to test on, but there's nothing near here.

45 MPG at 55-60 is where I'm at. Still aiming for a 50 MPG tank. Finishing up the aero nose now, getting ready to bolt up the rear bellypan.