TRexian has released a JTD Ambient Civilian Traffic module on the BI Forums.
The idea for this was born of the great work BI did on the civilian modules. With civs and vehicles in the same town, it only made sense to have them drive around. (There is a small - VERY small - chance of this when you put the ALICE and SILVIE modules in together, but it wasn't enough for me.) So, I developed this. It relies on the ALICE module to spawn the civs and vehicles. I consider this a public release candidate. If there are no issues, I'll just update from here