Question about Cruise Control...
 

Does Cruise control effect MPG?...If so, by how much?

Uhm, how? Using cruise control is the same as holding the pedal steady. Why would it change MPG? Other than if you use it at a steady 70MPH you'll get better mileage thean cruising at 85.

I think cruise control generally improves mileage. Driving by pedal inherently causes slight velocity fluctuations, and that extra tiny bit of acceleration that you may not even notice adds up over time. Cruise control eliminates those little speed changes, and improves MPG because of it.

Ditto to kbull's comment. Cruise control will only add just the amount of throttle to maintain a chosen speed (it does not hold at a constant throttle position which would result in different speeds for uphill/downhill, etc). However, if you drive moderately, the difference between using cruise control and not can be insignificant.

after 6 gear i think it would help.

Also, a comment about the cruise control- this has to be the tightest control system I've ever seen. Most cruise controls don't account for speed variations until you're maybe +/- 5 to 10 MPH from your desired speed. When I'd set the cruise in my Accord, say at 75 MPH, it wouldn't kick in until the car was going just about 65. Then, it would take about a minute to get the car back up to 75. I never understood that. The 8 is a different beast, though. As soon as you hit "set", you're locked into your current speed- no variation at all. A much better system, IMHO.

Think you have a bad Accord. That is too much variation.

The 8 is very precise, but a little too responsive when clicking 1 mph either way. It causes my passanger to notice the change. We also have a 2001 Dodge Intrepid. It's cruise is almost as precise as the 8, but smoother. Also gets 28~29 mpg at 75mph, but not as much fun to drive.

Generally a cruise will inprove milage by holding the throttle steady. But the professional gas milage drivers can do better by thinking ahead. As in rolling hills. Let the downhill speed go up so you don't need to add throttle as soon on the next climb. Then let the speed drop some near the top of the hill. Understand?

By the way you should get into 6th as soon as possible with the 8 if milage is what you want. Once the rotary is warmed up it can actually pull 6th from ~1500 rpm (if you don't need to accellerate, like in trafic). I commonly use 6th from ~ 35mph on the city streets and get 18~19 around town (with an occasional 9000 rpm push).

I'd have to ask what year is your Accord? With my Accords (1994 and 2003), When I set 75, it stays strictly at 75. It will even downshift going up and down hills (at least in the 03 Accord to use engine braking) to maintain 75 MPH. And with my old 94 Accord, if I press resume when I'm going 25 and the cruise is set at 75, it tries to get to 75 as fast as possible! It's amusing to see the cruise control logic floor the accelerator to speed up to 75. The 03 Accord isn't quite so bad about that.