What vehicles do subs sound the best in?

im getting anew car and i want to make to make it around audio because im starting to love subwoofers more and more. i have 3 rockford fosgate p2's in a 6.4 cubic foot sealed box. they dont fit in my old car which is ok because i was selling it anyways so i tryed the subs in my friends grand am just in the back seat and it sounded great then i tryed it in my friends bronco which is kinda big and it wasnt loud at all to tell you the truth... so would a small SUV be good thing to buy?