1cm shouldn't really cause a problem. i've done it before. but i've got a 1,8L engine. yaris have a 1.3L in the povo spec and 1,5L in the higher range. so the ratio to overfilling by 1cm would be different. if you're that worried just drain abit out of the sump and away you go... when i overfilled it, i had to drain it out and put it back in. also check if your driveway is on an angle, might not look as bad as it is. but going by what u said: 1L overfill is quite a lot on a yaris engine.