40 CFR § 610.23 - Operator interaction effects.
---
identifier: "/us/cfr/t40/s610.23"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 610.23 - Operator interaction effects."
title_number: 40
title_name: "Protection of Environment"
section_number: "610.23"
section_name: "Operator interaction effects."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "Q"
subchapter_name: "ENERGY POLICY"
part_number: "610"
part_name: "FUEL ECONOMY RETROFIT DEVICES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "Sec. 511, Motor Vehicle Information and Cost Savings Act, as amended (sec. 301, Pub. L. 94-163, 89 Stat. 915 (15 U.S.C. 2011))."
regulatory_source: "44 FR 17946, Mar. 23, 1979, unless otherwise noted."
cfr_part: "610"
---
# 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.