The best (by far) that I travelled on today was a B-class on route 75 - it was practically icy inside and very comfortable despite the heat. I had a C-class Alstom on route 109 that was 'okay' but not nearly as good at the B (maybe because of the large windows capturing more of the sun). The worst (by far) were the Siemens D class - I travelled on at least three today and each and every one was unbearably hot inside... almost no noticeable difference between inside and outside of the trams and the worst part is that unlike a Z-class you can't even open a window to get a breeze going as it travels along. National Express and Siemens obviously didn't do any design modifications for Melbourne summers when they bought them over - disgraceful that for the millions spent on the fleet they wilt in the heat.
How is it that a 20+ year old tram has the best air con by far and the most modern ones are dreadful?