HEIDHAUSEN

First time posting a new thread. Just had my 320 serviced with new plugs and wires using book recommended replacements. Noticed around a 5mpg increase in fuel consumption on daily drives for a week now. No hesitation, no engine roughness, starts and idles fine. 150,000 miles. Plugs seated and wires to each cylinder not crossed (unless all of them are, as they all match). Would that even cause this issue? No malfunction codes. Same mechanic will be taking a look at it next week but wanted to have some basic info in order to keep up with any subsequent conversation. I used to get around 29mpg and now get 23.5 mpg on average. Accelerates fine, no new vibrations, noises, hiccups.
Bud

exhaustgases

Maybe some sub standard parts were used, causing less efficient combustion.
Some times its best not to fix what isn't broke.

burgca

Did you change plugs and wires as preventative maintenance or was there an issue? If there was an issue you may be enjoying the drive with more robust enthusiasm.

HEIDHAUSEN

I was the second owner buying at 69,000 miles. Once I got to 150,000 and it seemed I was sensing some hesitation on acceleration I figured I might be running on original plugs so I changed them. Also figured that while changing plugs might as well change the wires.