The best maps to use in the car are iMAPs. They cover
Dubai, Abu Dhabi and Al Ain, Sharjah and Ajman, as well as the Northern Emirates.(there's 4 in total)
They are brilliant, detailed, indexed and even have 3D maps included for the areas you want to walk around such as the Dubai Creek and the Sharjah Heritage and Arts areas.
They also come in a very durable plastic sleeve. Also only Dhs25.
I sound like a salesman but they really are great. Got mine at Magrudy's.
Took the address off the map if you need it: info@3d-imaps.com
Hope this helps. X