Each car really needs to be evaluated individually by looking at the auction sheet translation. But in a nutshell the grades can be outlined as
Grade 5/S: New condition
Grade 4.5: Very lightly used condition (usually reserved for very low km cars)
Grade 4: Used condition with only light blemishes
Grade 3.5: Good condition with more noticeable blemishes
Grade 3: Average condition with marks and possible poor paint or light damage
Grade 2: Poor condition may have accident damage or corrosion
Grade 1/0: Rarely used – generally means heavily modified or a car with lots of alterations
Grade R/Ra/R1/R2: Accident repaired car or a car with an inner panel replaced.. can vary from extremely minor repair to heavily damaged car – Always ask for a translation