Yes, 1kr-fe, the worst engine i have experienced so far. i have kept 3 Vitz and have test driven many more, all of them had this stupid vibration problem, the car rattled like hell, no pick and performance, high octane used to hide the problem, and its not just that the engine wasn't healthy, fresh import and very low mile genuine highly maintained cars had this issue, High-Octane did cover it though.
About Passo, 2 weeks back i went to see a Passo Racy. The engine was like a cancer patient on ventilator, or a girl being r*ped, but that car had issues, a friend had a Boon(same as passo) and that was smooth silk