Car, and I accelerated OH SO SLIGHTLY! And guess what. I felt the SLIGHT acceleration. Which puts me in the belief that if I cannot feel it, its not happening. I feel my self being slightly pulled to the ground, especially when I jump. I DO NOT feel acceleration though, AT ALL. Like I said, I was in my car, I accelerated OH, OH OH so slightly, and I felt it. If our earth is accelerating so fast, I would feel it.
Which concludes: We are not accelerating. Merely, a force of gravitation is holding us down.