@up: yes. Standard GTA IV timecyc is about 80 kb, for some reason custom ones have only 45-50. And these 100 kb are per weather. Weathers are called
Also I counted the vehicles in handling.dat:
178 cars & trucks
13 planes (3 more are commented, seemed to be in alpha but not in release)
15 truck trailers
5 special cars (bulldozer, tank etc)
and something called "blimp" IDK what this should be.
158 km/h seems to be maximum speed I found, a car called carboniz. Seems to be slow but I expect the same scale like in GTA IV where when you used a ground with 10 meters grid and drove over it and measured the distance and time the actual speed was much higher than set in handling file.