Yes brother you are right this is what happens when you are on road. Thanks for your kind words.
Dear, rear seat of my vitz is adjustable and i have placed a 60 liter cylinder at extreme back position. So by pushing my back seat to front side i get reasonable space to put things in trunk. A couple of months' back i loaded my vitz with 40 KG flour bag, 4 medium size cloths' bags and 3-4 shopers. 4 passengers were also there. SO WHAT ELSE ONE WOULD EXPECT FROM VITZ???
Here in Islamabad/Rwp temperature has been -2 to -3 at night time but never faced any such problem of transmission. So it cannot be due to cold weather conditions. However, as others have mentioned check atf oil etc. As per recommendation of Toyota technicians in Rwp atf should be changed very 50 k KMs.
I dont know right or wrong, but there is common perception about platz that it is an under-power vehicle, i.e. body is bit heavier/bigger for 1000 cc engine.