There are 2 causes for no cars in the builtin routes in 2009. One is the region tag in the routes config.txt file and the second is the presence of the line:
holdcarz 1
in the routes config.txt file.
Check the config.txt file of any route that you want to have carz in, if holdcarz 1 is present, delete that line, save and commit. If that isn't the problem make sure the region is one of these:
Australia,<kuid:-1:7801>
United States,<kuid:-1:7804>
France,<kuid:149301:1003>
HP-Trainz Region Elbtal,<kuid:68787:1266>
SDW.2.1 Region Thuringen Romantik,<kuid2:121616:100901:1>
PTP Region,<kuid:151900:1>
If you make any change be sure to save and commit.
Bob