Interesting physics problem.
A Model S weighs about 4,800 pounds.
If you go over a 3" speed bump with all four wheels, you can roughly assume that the car is elevated 3" off the ground, and falls. This is a "potential energy" calculation.
Using this web site,
Grab the potential energy calculator to find how much energy is stored in an object raised off the ground.
www.omnicalculator.com
A Model S falling 3" equals 0.000451 kW*hr.
If you have an 85 kW*hr battery, this equals roughly 200,000 speed bumps for one charge.
Interesting math, but obviously not worth the parts cost and engineering labor time for Tesla.
Brian