{"data":{"id":"us/40-cfr-610.41","jurisdiction":"us","citation":"40 CFR 610.41","heading":"Test configurations.","body":"(a) In order to measure the effectiveness of a retrofit device at least two, and in some cases, three vehicle configurations defined in § 610.11 will be tested. Each vehicle will be tested at least twice in each configuration, as determined by the Administrator.\n(b) The first test configuration is a baseline configuration. In this configuration the baseline or unretrofitted vehicle emissions will be measured.\n(c) A second test configuration, an adjusted configuration, may be required at the discretion of the Administrator if a device requires both hardware and engine parameter modifications to achieve the fuel economy improvement. If, in the Administrator's judgment, based on a review of the available information, the combined effects of retrofit hardware installation and parametric adjustment could be substantially duplicated by parametric adjustment alone, then the Administrator may specify a second test, to evaluate such adjustment exclusive of the retrofit hardware.\n(d) The third series of tests, in the retrofitted configuration, will evaluate the full retrofit system installed on the vehicle.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER Q—ENERGY POLICY","PART 610—FUEL ECONOMY RETROFIT DEVICES","Subpart D—General Vehicle Test Procedures"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"1599ccff4421a0e4c4728277b9f6c33e1139df0dcca1014e522deb67837e8ac5","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-610.40","next":"us/40-cfr-610.42"},"notice":"GroundRules: Original legal text. Not legal advice."}