I have some Hot Wheels cars that are reasonably close. They are supposed to be 1/64 but the scale is not consistent and the ones I have are 1/60. Which is my preference anyway, and on the up side they only cost .84 cents each.
Brigade games carries a number of CompanyB interwar vehicles, Model T's of various types and a Mercedes truck, plus armored vehicles and tanks. and Bluemoon manufacturing's Highways and Byways series has a dozen or so cars and trucks appropriate to the time period. I don't own any of these so I can't actually vouch for how close they are to scale.
http://www.brigadegames.com/Interwar-Vehicles_c_241.htmlhttp://bluemoonmanufacturing.com/index.php?cat_id=18