as far as accuracy goes, every time i pass a street radar sign , i don't know if you have them in your city, state, in so. calif. we have everything [ just can't pay for it ha ] anyway it actually shoots a radar beam at oncoming traffic and displays your speed , to make you aware and if necessary slow down. my point being, my dig. speedo has been spot on , i couldn't say for the tac. as you probably know it has many functions, 2 trip meters dig rpm and analog rpm, total hours [ run time ] turn sig indicators, high beam indicator, gear , clock,..... thats all i can think of, its a very compact unit, i still like mine.