Here is a question I received and answered on the now-defunct website AllExperts.com:

My daughter is learning how to drive. Her hand position is 8 and 4. I asked her driving teacher, we used to 10 & 2 or 9 & 2. The teacher says it is for airbag safety. Do you like their saying for now a day.

So, yes, the official recommendations for hand position have changed over time.  Up until the early 1990’s, the standard was to keep your hands at 10 and 2.  But starting around 1992, airbags became standard equipment, and the steering wheels actually got smaller (next time you see a vintage car in a parking lot, take a look at how huge the steering wheel is compared with a newer car).  

The best possible hand position is 9 and 3 – directly across from each other, horizontal along the center of the wheel.  In a modern car, this position allows you the most athletic grip on the wheel and the most precise control of the car.  It also allows you to make sharp emergency and evasive maneuvers efficiently.  Hand positions of 10 and 2 or 8 and 4 limit effective control of the wheel by restricting arm movement needlessly.  Finally, a position of 9 and 3 also allows you to access many of the vehicle controls (turn signals, wipers, bluetooth, stereo, cruise control, horn) without taking your hands off the wheel.

We’ve also moved away from hand-over-hand steering, and instead recommend shuffle or hand-to-hand steering.  This both reduces oversteer and also prevents the arms from crossing in front of the airbag, which can cause serious injuries if the bag deploys.  A quick search on YouTube should give you some great examples of how to do shuffle steering.

These are the latest teaching recommendations, based upon the latest research and adapted to the latest technology.  If your driving instructor is recommending anything else, find a new instructor.