First check the air in your tires. Some people have reported low tires comeing from the factory. If you feel comfortable you can boost the preasure up to max sidewall presure. This will increase FE. I can't realy talk about the rumble/shudder because I haven't driven an accord. Also, what gear to you drive in? I believe there is a drive and overdrive and a few others (again not 100% sure because of my lack of experience.)

My hydroponics experiment

You ever notice how hard it is to lip read cartoon characters?
"Crazy is what the sane call Delta Flyer"