I had a trip this July to Abu Dhabi/Dubai. The road from Salwa to Saudi/UAE border is dual carriage way, two lanes each. This 130 km stretch road is in good condition. However, sandstorm sometimes brings sand encroaching the road up to half of it. No street light so avoid driving at night. No camera. Only 1 gas station available (about 14 km before Sila border) and another one about 2 km after border (at nother side of the road). I suggest you to have full tank when leaving Doha. No international chain shops in gas station but juice stalls are available.

From here 330-350km to Abu Dhabi. The road is also dual carriageway two lanes each. The road is ok but expect diversions (one or two near small towns). There are lots of solar powered cameras but don't know if they are working. From Abu Dhabi to Dubai the 4-6 lanes road is excellent. From Sila border to Abu Dhabi, gas stations are normally available in every small towns such as Al Sila, Al Hamra, Ruwais, Mirfa, Tarif. One full tank from Sila border is enough to drive you to Abu Dhabi.

Please visit my blog about my journey there.
http://wahyuinqatar.wordpress.com/category/uae-oman/