E-coat is a replacement for zinc coating which is not allowed for environmental reasons and it is nowhere as effective as zinc coating.
After that they just paint on top of that, so that’s most likely what the black, smooth finish is. It will be fine for around 10 years.
If OP plans to keep this vehicle 10+ years, rustproofing, not to be confused with undercoating, is a good preventative measure. It helps with fasteners corrosion, various bracketry, evap leaks and generally things from being stuck.
After that they just paint on top of that, so that’s most likely what the black, smooth finish is. It will be fine for around 10 years.
If OP plans to keep this vehicle 10+ years, rustproofing, not to be confused with undercoating, is a good preventative measure. It helps with fasteners corrosion, various bracketry, evap leaks and generally things from being stuck.