hi i have the 2007 vitz and today i found the same thing. but when stoped at a colour light the engine is little kind of picked up and try to go front and some times the kind of a vibration have sen. but today after driving for 20 km s, i found when parked by engine is vibrating little un usual. not sure why. i hvae dropped a mail to toyota lanka. let me wait for their reply too. i chnaged oil, oil filter, air filter with toyota genuine stuff. it has ran for 80000kms. if anyone can help me please welcome.