Examine a data base containing thousands of in-bays at gas stations and convenience stores and you would find roughly a 5 to 6 percent difference in total operating expense, friction being less than touch-free.
The chemical expense for friction is less than touch-free but maintenance expense for friction is greater than touch-free. Claim expenses are higher for friction but this has changed significantly with the advent and penetration of foam cleaning material.
Surprisingly, there is only a slight difference in water and sewer expenses in this data base, friction slightly less than touch-free. The why is because touch-free can use twice the water as friction and, therefore, there is a higher presence of reclaim in the touch-free population.
So, if you want a fair comparison, visit OEM sites and gather the specs for the machines you are considering. For instance, if you visit Autec website, among others, you will find typical cost of operation for machines.
http://www.autec-carwash.com/pdf/EV-1ChemWaterTime.pdf
Bud did bring up a salient point, indirectly.
For many self-service owners, friction or touch-free is a matter of personal choice. For others, like gas/c-store chains that have networks of washes the issue is a business decision. Clearly, the competition has been gravitating towards friction-only and hybrid.
Over the most recent three year period for which data is available, the ratio of friction to touch-free equipment spending has changed from 36 percent / 64 percent to 46 percent / 54 percent.
Due to the increasing cost to operate a touch-free in-bay (chemical and water) and improvements in friction technology, little disruptive change is expected in the trend towards friction/hybrid in-bays.