Great purchase and welcome to the Volt family! At 5 years old, you're looking at a coolant system flush and fill. Also, at 45k miles Chevy recommends a transmission fluid change (on a severe schedule however I would argue fleet use qualifies for that). If you don't have proof that these things were done, don't assume the state did it while they owned it nor that the dealer did it before resale. Also, check the engine and cabin air filters. At only 16% EV use, the REx has seen quite a bit of use. Another user posted recently that they recently purchased a prior fleet use vehicle and many of those simple maintenance things were overlooked while in fleet use and the dealer he bought it from didn't do anything to it prior to selling.