Was my punishment harsh?

I took my dad's car without permission today. He gave me a choice of a real hard bare bottom spanking with a belt and a paddle or being grounded for a month, so I took the spanking. My dad spanked me 20 times with a belt on my bare bottom. My bottom has welts and is swollen and sore. It hurts to sit down. It was worth it to get it over and not be grounded. I haven't been spanked since I was 12. My older brothers are 16 and 18 and they both get belted and paddled on their bare bottoms. Do you think my dad spanked me too hard? Do you think 14 is too old to get spanked?