Excerpts from an old threat by a member named Stablok. As he said take several readings at full speed in both directions and use an average. You'll end up with a pretty good idea (if not completely accurate) of how fast you're going.

"There is an easy way to figure how fast your truck is at top speed.

Draw two lines 100 feet apart. You'll need room on either side of the lines for braking and to reach your top speed . Do it on a nice level road. Then you'll need a stop watch and someone to time you. Get your truck up to operating temperature and do a run. You want your truck to be at top speed when you hit the first line and continue until you hit the second line. Get that someone to start the timer as soon as your truck starts to cross the first line. That someone will have to stop the timer as soon as your truck starts to cross the second line. Do it a few time. This will allow the time keeper to get some practice on the timing. Then, do it several time in both direction and record each time. Now, with your calculator, take 100 divide by your average time and multiply that by .68 and it will give you your speed in mph. So if your average time between lines is 1.8 seconds then it's 100/1.8x.68=37.77 mph."


His calculations.

1 mile = 5280 feet.

If it takes you 1 hour to drive 5280 feet, then you drove 1 mph.

1 hour = 60 minutes = 3600 seconds

3600 seconds / 5280 feet = .68181818181818

So, however many feet divided by however many seconds times .68 will give you MPH.

I suggest you do it over 100 feet for several reasons. The accuracy on the person timing the run for one thing. Anything less then 100 feet will be hard to time accurately. And anything over 100 feet, well, I would want to hold my throttle wide open that long."

And some other intresting info.

"1 tank holds 160 cc of fuel
1 Gallon = 3785.4118 cc
1 Gallon = 23.658823 tanks of fuel
1 Gallon = $26.00 (canadian)
$.90 = 1 tank of fuel
1 tank = 15 to 20 minutes
each minute = $.04 to $.06 of fuel."