Can an iPad be used as in car entertainment, are there accessories to install it in your car?

have you tried Google?

There are various mounts available.

http://gripdaddymounts.com/index.php?p=1_9

http://gripdaddymounts.com/index.php?p=1_10

http://www.arkon.com/iPad_accessories/ipad_car_mount.html

http://toucoul.com/products/coulvue-headrest-car-mount

http://usa.luxa2.com/product_showroom.aspx?s=46

You can find several videos on Youtube demonstrating how you can install your iPad in your car.... a little bit tricky though.....

Check this one :

http://www.youtube.com/watch?v=rSnIXfoSU6I&feature=relmfu

Search for "iPad car install" for more !

Good luck !