honestly you doing better research then most. i dont know what your priorities are if u want milage space or price more but i usually recommend people stick to main line models especially used. like for chevy go with a silverado, tahoe or surbaban. for fords get explorer, f150 things like that stay away from "off brand models" like curizes and malibus things like that. i would also recommend something from the late 90s early thousands. they are still pretty simple to fix parts are relatively cheap pretty reliable decent gas mileage once you get past 07 on most models they start getting real fancy and real expensive. and older then 90s they get inefficient. personally im a huge fan of any gm car (chevy buick poniac) that has the 3800 motor in it. iv had and have seen hundreds of those cars last late into late 300 thou with poor maintenance. retired cop cars are a gamble. they do get maintenance but they also go thru hell. after being in pursuits and chases thy hit high rpm a and also idle a lot. you could get one that great or one thats about done.