The built-in region kuids for TRS2006 are:
Australia,<kuid:-1:7801>
United Kingdom,<kuid:-1:7803>
United States,<kuid:-1:7804>
Germany,<kuid:-1:7808>
 
You could clone one of those, rename it and add your own list of cars.  I cloned one but completely edited its config.txt file using Notepad.  The tag ontheright makes it drive on the right.  Here is the config.txt file:
kuid      <kuid:47907:1118>
trainz-build     2
category-class      "YX"
username      "Bobs Cars"
kind       "region"
region       "USA"
watercolor      38,74,92
ontheright      1
defaultjunction      100634
longitude      77,1.2,-1
latitude      38,53.4,1
altitude      0
car0       <kuid:67261:29007>
car1       <kuid:67261:29009>
car2       <kuid:68787:22157>
car3       <kuid:68787:22162>
car4       <kuid:67261:29012>
car5       <kuid:68787:22166>
car6       <kuid:68787:22167>
car7       <kuid:67261:29015>
car8       <kuid:68787:22164>
car9       <kuid:68787:25068>
car10       <kuid:67261:29018>
car11       <kuid:68787:22159>
car12       <kuid:67261:29021>
car13       <kuid:68787:22163>
car14       <kuid:67261:29022>
car15       <kuid:68787:22158>
 
Bob