Two words: OFFICER SAFETY. These cars are ran hard and put up wet. Kansas obviously understands that its' officers lives and well being are worth the extra precaution of replacing the car before anythng major needs servicing. Also, it's dollars and cents. They probably get a decent price for the cars with only 50,000 miles on them, plus they avoid big ticket repair items such as shocks, rotors, cooling system, air conditioning condensers, brake lines, etc. and other costly engine maintenance items,