Modern 1/35 civillian vehicles

There is definitely not much available- that is not a common model car scale.  There is plenty of 1:32 scale stuff, but that is ten percent off scale (I like to keep all diorama stuff within 5%).  Depending on what other stuff you have in the diorama you may get away with it.  These larger cars should be towards front of diorama, certainly not back of scene, if you do use them.

One vehicle I'm trying to find is a burnt out car by MiG productions.  I think it's out of production though.  If I find one I can use stuff from my parts box to make it look like a runner.

You are going to have a seriously hard time finding cats to match a 1/35th Dio, trust me on this.  Your best bet is to either use larger cars, such a trucks and SUVs in 1/32nd.  They are big enough that you wont notice the difference, OR, just use 1/32nd figures

Aside from those new Toyota 4x4/ Technical releases, there is next to nothing out there in current 1/35 civilian vehicles. For older cars Tamiya makes an "impressed" Citroen and I think CMK makes the original VW Beetle that can be converted to civvy cars fairly easily. And Italeri makes a 1/35 long wheel base Landrover with a hard top that can be modified to street clothes/colors.