I just had a neat idea ( I think)--
I found my old aviation whiz wheel, and it made me think, "Wy can't you make a time-speed-distance whiz wheel you could use (or co-driver) while you are travelling down the road?
Is there any software that allows you to print a whiz wheel thing, or would you have to draw it by hand?
I haven't worked out details yet, but it involves matching time & distance for initial speed, then you adjust it to your odometer and timer while driving to get the new speed to go. the whiz wheel should be safer than using a calculator, meaning it should only take a sec or two to look at & adjust the wheel, then another sec or two to read it. I'm sure I could write a program for my notebook computer or PDA (*choke!*), then keep it on the seat (notebook) or velcro it to the dash (PDA).
just a thought, and
I'm full of it.