I read the ZZ (vs. 4A/7A) engine was designed such that it's lighter plus the heat is transferred more efficiently from inside to outside. From the analysis of the writer, it was really a brilliant design. I think for olders, some mods on the internal include this scheme of getting the heat out efficiently. Will post the link if I see it.
i've had my vios for 1.5 years na (1.5g a/t). overheating is no problem. the coolant level goes down very slowly and the radiator doesn't even need to be refilled in between preventive maintainance. i don't know why the lack of a temperature gauge is such a big thing.
Siguro magiging issue na ito pag medyo matanda na ang car. Pag bago pa lang, okay lang na warning lamp ang indicator mo. Pag lumalabas na mga tama sa makina, minsan di mo na namamalayan mainit na pala. Experience ko sa XE ng friend ko bigla namin nakita nasa gitna na ang meter. At least pag gauge matatantsa mo pa kung hanggang saan pa kaya ng engine.
i drove the vios so many times na, ayun nga wala talagang temp gauge at ayoko ng ganon, mas maganda pa rin yung merong analog temp gauge rather than that warning light. eh pano kapag luma na kotse mo makakasigurado ka ba na di tumataas temp mo>>>??? speaking of med rep ako rin naaangasan ako sa mga yan akala mo kung sino!!! mas maganda sana kung ginawa nila na digital at least alam mo talaga pagtaas at pagbaba ng temp mo. pero mejo nakakailang siguro kapag ganon hehe kasi lagi mo na lang yun titignan. i visited a toyota showroom at tiningnan ko ang vios(nung bagong labas pa lang), i asked the sales agent kung asan temp gauge ng vios sabi nya sir meron po sabi ko asan nga di ko makita yun pala baguhan sya nung pinaturo ko sa kanya di naman nya maituro ntawa na lang ako at lumabas ng showroom. bwahahaha.