[Code of Federal Regulations] [Title 40, Volume 29] [Revised as of July 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR610.23] [Page 1003] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 610_FUEL ECONOMY RETROFIT DEVICES--Table of Contents Subpart B_Evaluation Criteria for the Preliminary Analysis Sec. 610.23 Operator interaction effects. The device will also be evaluated with respect to: (a) The degree of sensitivity of device effectiveness to variances in installation, operation and maintenance; (b) The adequacy of manufacturer-furnished instructions for minimizing variances in installation, operation and maintenance; (c) The extent to which device installation or use, or the effects of such installation or use, relate to Federal emission control regulations; (d) Effects on the performance, safety, or occupant comfort of the retrofitted vehicle, and on that of other vehicles; and (e) The relationship between total cost of ownership of the device (purchase price plus maintenance costs) and the cost savings realizable from its fuel economy effects.