"Hello. Is steeling car is criminal case or civil case?"
*** It IS a criminal case, and could be a civil case since the owner and/or insurance company can come after you to recover their 'damages' caused by you.
"What is the highest punishment can you get if caught after auto theft?"
*** Washington Revised Code:
"RCW 9A.56.070
Taking motor vehicle without permission.
(2)(a) A person is guilty of taking a motor vehicle without permission in the second degree if he or she, without the permission of the owner or person entitled to possession, intentionally takes or drives away any automobile or motor vehicle, whether propelled by steam, electricity, or internal combustion engine, that is the property of another, or he or she voluntarily rides in or upon the automobile or motor vehicle with knowledge of the fact that the automobile or motor vehicle was unlawfully taken.
(b) Taking a motor vehicle without permission in the second degree is a class C felony."
RCW 9A.20.021
Maximum sentences for crimes committed July 1, 1984, and after.
(c) For a class C felony, by confinement in a state correctional institution for five years, or by a fine in an amount fixed by the court of ten thousand dollars, or by both such confinement and fine.
The actual sentence that you may receive is based on a complex 'sentencing grade' that would evaluate prior history and other factors and set your sentencing levels.