Take a look at an awesome HDRI pack by Panocapture full of backplates.
Images shot with a full frame DSLR using a Nikon 16mm full frame fisheye lens mounted on a nodal panoramic head and shot with a 12 exposure range. Backplate images were shot at the same time as the HDRI with a 35mm prime lens and are 6016×4016 pixel resolution. These are fantastic high-resolution environments to use for automotive or general vehicle rendering.
HDRI maps are 16000 x 8000 and 12 stop exposure. Backplates are 24 megapixels.