TRAFFIC FLOW V5
An update to Traffic Flow has been requested by quite a lot of people and today, after installing some car mods for the first time in ages - I felt motivated to update TFM.
Unlike previous versions, TFM V5 doesn't actually spawn any cars, instead it loads between 2 to 5 randomly selected vehicles from a configurable vehicle pool into GTA IV's memory, making the game prioritise those cars to be spawned rather than taxis. This results in the traffic becoming much more diverse and partially solves the 'taxi bug'.
In the TrafficFlow.ini, there is a vehicle pool with 20 models, you can change these models around as you please. The default TrafficFlow.ini file seems to provide a fairly balanced traffic composition, however.
Be warned, if you are running GTA IV with anything under 2GB of RAM, you shouldn't use this script or any car mods at all.