You have to first cross qatar border, then after around 3 KM, you will find saudi border

Crossing Qatar Border:
- First go to the first counter (go with car - no need to park the car)
- Give "car istimara" (car registration)
- they will enter your details and will return the istimara along with a slip
- Drive to second counter - Give your passports
- they will stamp your passport (Exit stamp)
- Go to the third counter - produce car slip + Passport
- He will cross check the details and reuturn you passport

Qatar exit complete

Crossing saudi border:
-Collect vehicle slip on the first counter
- After first counter - park your car
- On the right side you can see visa office
- Go inside and give your passport to the officer
- He will do your finger print and picture (for ladies finger print is on another room - officer will guide you)
- now take your car go to the second counter
- Give passport and car slip to the counter
- He will stamp your passport (Saudi entry stamp)
- Now drive 20 mtrs and do car inspection (they will just check your car)
- While going to the third counter, you can see a small counter for car insurance (100 DHRMS) you have to take car insurance
- drive to the last counter, show the security all your documents (passport + Car slip+ etc.)

DONE! you are in saudi now

After few km you can see a round about (left going UAE) - straight going saudi

Driving Plans:

Border - Hofuf (no need to enter hofuf city) - Express highway - Riyadh - Sail al Kabeer (before Taif take right- Your meeqat is here)- Makkah

Let me know if you need further assistance