I bought a '98 civic dx a few weeks ago. Not exactly the car I was looking for (waiting on a VX), but this one is almost rust free, and the price was OK.
I installed my Ultra Gauge on the car, and without any calibrations, it was reading right around 40mpg at 55mph. This probably on the high side, but we'll see. My first full tank of gas is almost gone, so I'll check the numbers soon.
Yesterday, I installed my custom built air dam. I bought 5 inch "contractor grade" edging for $16 at the local Home Depot. There really isn't much to bolt an air dam to under this car. There are 5 bolts that hold the plastic bumper to the frame. I used 3 of these to hold my plywood to the underside of the car. Step one was to make a template of the underside of the bumper. I used some old blue insulation I had in my shop to do this. My daughter helped me hold the foam board under the car while I cut it using a razor blade. Then, I traced the shape on to a 1/2 inch piece of plywood, and cut it out using a jig saw. I then reinforced the edge with more plywood. The next step was to screw the edging onto the plywood. This was fairly easy, with the help of my youngest son. The trickiest part was trying to find the holes to secure the plywood to the frame. I little messing around, and I got 'em in. I also cut out the slots for the tow hooks so the plywood would lay snug under the car. I figure this plywood frame would be nice to attach a belly pan to in the future if I ever decide to do it. I drove the car down the road after I installed the dam, and sure enough, I scraped it on a few spots on my old town road I live on. These are big bumps in the road, so I wasn't surprised it scraped.
So, going 55mph on a flat road, the gauge was hovering around 44mpg. I picked up .4mpg also in a 10 mile trip. I believe it was worth the effort.
Removal will be a snap. Undo 3 bolts, it's off.
