Did a check on Illinois out of curiosity and the IL EPA has a testing program for Chicago and East St Louis for 1996 and newer cars. Anything built before 1995 in those areas I guess has to be unmodified, but won't be tested otherwise. Anywhere else in the state no one is watching. If it is a 1992 or older vehicle in Chicago and East St Louis, and has an antique plate or expanded use antique plate (mine does, unrestricted driving from April through October) is exempt from testing.
Since the Chevy inline six was done with the last 250 Varajet and 292 full size trucks in I think 1987, all inlines are exempt from inspection and testing here for antique plates. Since regular plates are annual $101, and the two antique plates are cheaper at $30/5yr and $51 annual, and our winters are no place for old rear wheel drive cars, there's no reason not to register them that way here.
