uštedeti

1. (of money, time, energy) to save
   Uštedeli smo dovoljno novca za letovanje. — We saved enough money for a summer holiday.
   Autoputem ćeš uštedeti pola sata. — You'll save half an hour on the motorway.
2. (someone (dat.) + acc.) to spare
   Tako ćeš sebi uštedeti mnogo muke. — That way you'll spare yourself a lot of trouble.

The imperfective is štedeti; "to save on something" is uštedeti na + loc.