Hi Terry, obviously this should not be happening to a 2013 era car, but it depends on what, if anything, the offending areas have been subjected to in the past. Do not use any solvent type cleaners, but try an internal detailer fluid, such as Meguiar's, to see what can be cleaned up. Do not spray the detailer direct onto the steering wheel surfaces, but onto a microfibre cloth and then work the solution into the cloth before tackling the control thumb wheels on the steering wheel. Work the areas around the controls and then wipe clean using a dry / clean microfibre cloth.
If the Meguiar's doesn't do the trick, mix up a weak solution of lukewarm water and washing up liquid. Again using a microfibre cloth, soak it in the prepared solution and wring it out thoroughly until the cloth is just moist / damp, once again work the cloth over the controls and then dry with a second cloth, or a hairdryer if you have gotten the area a bit too wet.
N6 JMX