recently purchased '99 HX w/ poor FE

[cured1]

Hello. I recently purchased a 1999 Civic HX after losing my CX when someone pulled out in front of me. I averaged 38mpg with the CX. I commute about 70 miles a day, 90% is highway. A/C on 50% of the time. Averaging 70mph. I'm averaging 32mpg after 5 tanks of gas in the HX. It has a manual trans, 217,000mi (30k on rebuilt motor) and steel wheels. First thing I did after buying it was get an oil change. I haven't done anything else yet other than new shocks/struts and tires.

What should I be looking for in trying to improve my numbers?

[GasSavers_Erik]

Inflate tires to max sidewall rating
Jack up each wheel and spin it to be sure that a brake isn't dragging.
See if there are any stored codes on your ECU related to the oxygen sensor.

[tradosaurus]

Tire pressure to max sidewall.
Check spark plugs, cleanliness and gap.
Fuel filter change.
Air filter check.

[bowtieguy]

slow down. 70mph will not yield great numbers even if the car was in "like new" condition!

[add|ct]

Yes, probably at 70 MPH, the lean-burn feature is not being used.

[theholycow]

What year was your CX?

The 1999 HX is rated a respectable 30/38. I expect your 70mph 50% A/C should do better than 32.

Do you know if the car has been modified? For example, is the gearing what it should be?

How about that engine rebuild...was it done to OEM spec or was it done with the intent of increased performance?

[1cheap1]

Check all hoses, check for vacuum leaks. check plug wires.

[cured1]

Thank you for the responses.

My CX was a 1994 model. I do not think the HX has been modified and I am unsure about the engine rebuild info.

I'll have a look at all that was suggested.

[tradosaurus]

Oh and don't forget one of these must have's for fuel efficiencies:

[theholycow]