Why does my mazda 626 run really high RPM s ?

5th gear is not a very tall gear so that RPM is just about right for interstate speeds

They geared it that way to have better performance off the line and out of corners. You'll notice that the automatic version of the same car will run at a much lower rpm at the same speed despite having fewer gears.

I'll check mine tomorrow,have to go on turnpike

i have an automatic and i have about 4-5k rpms when hitting about 60 and if i go faster then 90 it stays at 5500