EPA Fuel Quality Standards — Gasoline, Diesel, and Fuel Additives

EPA's fuel quality standards — consolidated in 40 CFR Part 1090 — govern the chemical composition of every gallon of gasoline and diesel sold in the United States. These rules set binding limits on sulfur, benzene, and other pollutants in motor fuel; establish the Reformulated Gasoline (RFG) program for the most ozone-polluted cities; require fuel additive registration and detergent additives in all gasoline; and set conditions for blending ethanol and other oxygenates. Part 1090 was consolidated in 2020 from a patchwork of separate fuel rules under EPA's Tier 3 Gasoline Standard (finalized 2014), the Ultra-Low Sulfur Diesel program, and the RFG program. It implements 42 U.S.C. § 7545 — the Clean Air Act's fuel regulation authority. The regulated community includes petroleum refiners (primary fuel manufacturers), importers, exporters, pipeline operators, terminal operators, oxygenate blenders, fuel additive manufacturers, and ultimately every retail gas station that handles product subject to chain-of-custody documentation requirements.

Current Rule (2026)

What This Rule Does

40 CFR Part 1090 is the primary federal rule governing the chemical composition of transportation fuels sold in the United States. It sets standards for gasoline purity, diesel sulfur content, fuel oxygenate blending, and fuel additive registration, while creating a compliance tracking system — batch certification, product transfer documents, and recordkeeping — that follows fuel from the refinery gate to the retail pump.

The central purpose is air quality: sulfur in gasoline poisons catalytic converters and increases vehicle emissions of hydrocarbons, carbon monoxide, and particulate matter. Benzene in gasoline is a Group 1 carcinogen and a VOC precursor to ground-level ozone. Reducing sulfur and benzene concentrations in fuel allows tailpipe emission control systems to work as designed over the life of the vehicle — which is why fuel standards and vehicle emission standards must be designed together. EPA's Tier 3 program cut gasoline sulfur from an average of 30 parts per million (ppm) to 10 ppm, harmonizing U.S. standards with California's Low Emission Vehicle (LEV III) standards.

Diesel fuel standards are equally stringent. The Ultra-Low Sulfur Diesel (ULSD) program cut diesel sulfur from 500 ppm (2006 Level 2 standards) to 15 ppm — enabling the diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems that now control soot and NOx from diesel engines. Without ULSD, these aftertreatment systems are rapidly poisoned by sulfur.

The Part 1090 compliance system works through a chain-of-custody: each batch of fuel is certified and designated at the refinery or importer level, documented on Product Transfer Documents (PTDs) that follow the fuel through distribution, and tested and retained at sampling points along the way. The system allows EPA to trace any fuel quality violation back through the distribution chain to its source.

Key Provisions

• § 1090.1 — Applicability: governs fuel quality standards for gasoline and diesel introduced into commerce in the United States; includes special provisions for Emission Control Area (ECA) marine fuel; does not apply to fuel exported from the U.S. before entering domestic commerce or to racing fuel not sold to the general public.
• § 1090.100–120 — Regulated parties: different compliance obligations apply to fuel manufacturers (refineries and importers), detergent blenders, oxygenate blenders, oxygenate producers, pipeline operators, and retailers. Any party meeting multiple definitions must comply with all applicable obligations.
• § 1090.205 — Gasoline sulfur standards:
  • Annual average standard: 10 ppm sulfur for each compliance period (calendar year)
  • Fuel manufacturing facility gate maximum: 80 ppm per-gallon standard
  • Downstream maximum: 95 ppm per-gallon at any point downstream of the manufacturer's gate
• § 1090.210 — Gasoline benzene standards:
  • Average standard: 0.62 volume percent per compliance period
  • Maximum average standard: 1.30 volume percent (the maximum annual average any single manufacturer may carry)
  • Per-gallon maximum: 4.00 volume percent at any point in distribution
• § 1090.215 — Reid Vapor Pressure (RVP) standards: all gasoline designated as "summer gasoline" or located anywhere in the U.S. during summer (June 1–September 15) is subject to a maximum RVP:
  • Federal standard: 9.0 psi maximum (most of the U.S.)
  • RFG areas: 7.8 psi maximum in Reformulated Gasoline covered areas during summer
  • E10 waiver: E10 blends receive a 1.0 psi RVP allowance above the otherwise applicable standard in most areas (meaning E10 may be up to 10.0 psi where 9.0 applies), unless the area has opted out under § 1090.297
• § 1090.220 — Reformulated Gasoline (RFG): gasoline used in RFG covered areas (high-ozone nonattainment areas — see § 1090.285) must comply with the standard sulfur and benzene limits plus RFG-specific requirements. RFG and its blendstock for oxygenate blending (RBOB) must meet the same per-gallon sulfur and annual average standards as other gasoline.
• § 1090.230 — E15 limitation: gasoline containing more than 10 volume percent ethanol (E15 or higher) may not be sold for use in:
  • Model year 2000 or older light-duty gasoline vehicles
  • Any heavy-duty gasoline vehicle or engine
  • Any highway or off-highway motorcycle
  • Any gasoline-powered nonroad engine (lawn mowers, generators, boats)
  • This makes E15 effectively limited to MY2001+ passenger cars and light trucks.
• § 1090.260 — Gasoline deposit control (detergent requirements): all gasoline sold to any motor vehicle must be treated with an EPA-registered detergent additive at or above the required treat rate; detergent blenders and oxygenate blenders must ensure compliance before adding to the distribution chain.
• § 1090.265 — Gasoline additive standards: any additive added to gasoline anywhere downstream must be registered under 40 CFR Part 79 and must contribute less than 10 ppm sulfur per gallon of additive.
• § 1090.270 — Oxygenate standards: oxygenates blended into gasoline (including denatured fuel ethanol) must meet a 10 ppm sulfur maximum per gallon; denatured fuel ethanol must additionally be composed solely of carbon, hydrogen, oxygen, nitrogen, and sulfur.
• § 1090.305 — Ultra-Low Sulfur Diesel (ULSD) standards:
  • Sulfur maximum: 15 ppm per gallon
  • Cetane index or aromatic content: minimum cetane index of 40, OR maximum aromatic content of 35 volume percent (either standard satisfies the requirement)
• § 1090.315 — Heating oil, kerosene, ECA marine fuel, and jet fuel: not subject to ULSD standards unless also designated as ULSD; specifically may not be sold for use in motor vehicles or nonroad equipment (the prohibition is on use in motor vehicles, not merely on the product itself).
• § 1090.325 — ECA marine fuel: ships operating in Emission Control Areas (North American ECA, covering 200 nautical miles from U.S./Canadian coastline) must use fuel with maximum 1,000 ppm sulfur; exemptions apply for steamships using residual fuel and for certain voyages where ECA fuel is unavailable.
• §§ 1090.700–799 (Subpart H) — Averaging, banking, and trading (ABT): gasoline manufacturers may generate sulfur and benzene credits when they produce cleaner fuel than required and bank those credits for future use or trade them to other manufacturers who need additional compliance flexibility. Credit transfers require registration and recordkeeping; credits expire if not used within specified periods.
• §§ 1090.800–899 (Subpart I) — Registration: fuel manufacturers, fuel additive manufacturers, regulated blendstock producers, oxygenate producers, and importers must register with EPA before commencing operations. Registration is facility-specific and must be updated when operations change.
• §§ 1090.1000–1090.1030 (Subpart K) — Batch certification and designation: manufacturers must certify each batch of gasoline, diesel, or regulated blendstock against applicable standards at the time of production or import; each batch receives a unique batch number; batch designations (ULSD, summer gasoline, RFG, RBOB) travel with the product through the PTD system.
• §§ 1090.1100–1090.1130 (Subpart L) — Product Transfer Documents (PTDs): on each occasion any person transfers custody or title of any covered fuel, they must provide a PTD to the recipient specifying the product type, batch number, designation, applicable standards, and transferor identity; PTD requirements do not apply to retail sales to the ultimate end user.
• § 1090.1200 — Recordkeeping: all records required by Part 1090 must be retained for 5 years from the date created; records relating to credit transfers must be kept by the transferor for 5 years from the date the credits were transferred.

How It Affects You

If you operate a refinery, import fuel, or blend oxygenates: You are a "regulated party" under Subpart B. Before commencing operations, register with EPA under Subpart I. For each batch of gasoline you produce or import, certify it against the applicable standards, assign a batch number, and designate it (e.g., "summer gasoline ULSD"?). Every custody transfer requires a PTD showing the designation. Annual sulfur and benzene averaging compliance must be reported. If your annual sulfur average exceeds 10 ppm, you must either purchase credits from the ABT program or carry forward the deficit under the overage repayment provisions. The Tier 3 standards represent a step-down from earlier standards — the compliance timeline staggered smaller refineries with extended compliance deadlines, but all domestic refiners are now on the standard program.

If you operate a gas station or fuel terminal: Retail sales to the ultimate end user are exempt from PTD requirements. But if your station also sells to wholesale purchaser-consumers (fleet accounts, commercial customers), Subpart P applies. You must accept PTDs from your supplier, retain them for 5 years, and pass them to any downstream custody transfer. Mixing of different designated fuels — especially mixing ULSD with heating oil, or mixing summer-designated and winter-designated gasoline — is restricted by the designation system. A station that mixes incompatible batches risks a violation even if the resulting blend tests within specs.

If you sell or use E15: E15 is legal only in MY2001+ passenger cars and light trucks. Stations that sell E15 must display the EPA-approved label at the pump and prevent dispensing to incompatible vehicles. Marine fuels, off-road equipment, motorcycles, and lawn and garden equipment must not use E15. The 1.0 psi RVP allowance for E10 generally does not apply to E15, creating additional volatility compliance challenges for E15 in summer.

If you operate vessels in U.S. waters: Ships operating within 200 nautical miles of U.S. or Canadian coasts must use ECA marine fuel at 1,000 ppm sulfur maximum. Global fuel sulfur standards (IMO 2020 cap of 0.5% for most vessels outside ECAs) are implemented through MARPOL Annex VI and enforced through the U.S. Coast Guard — not through 40 CFR Part 1090. However, vessels calling at U.S. ports may be subject to both EPA and Coast Guard fuel requirements.

Reformulated Gasoline (RFG) Covered Areas

Under § 1090.285, RFG is required in certain metropolitan areas with the most serious ozone nonattainment designations. Mandatory RFG areas (specified by statute at 42 U.S.C. § 7545(k)(10)(D)) include:

• Los Angeles–Anaheim–Riverside (California)
• San Diego County (California)
• Houston–Galveston (Texas)
• Chicago–Gary–Lake County (Illinois/Indiana)
• Milwaukee–Racine (Wisconsin)
• New York–Northern New Jersey–Long Island (New York/New Jersey/Connecticut)
• Baltimore (Maryland)
• Philadelphia–Wilmington–Trenton (Pennsylvania/New Jersey/Delaware)
• Hartford–New Haven–Springfield (Connecticut)

Many additional areas have voluntarily opted into RFG. Any area reclassified as a Severe ozone nonattainment area automatically joins the RFG program one year after reclassification (§ 1090.290).

Implementing Regulations — Renewable Fuel Standard (40 CFR Part 80)

While Part 1090 governs fuel composition and quality standards, the Renewable Fuel Standard (RFS) — the program mandating increasing volumes of renewable fuel blended into the national fuel supply — lives at 40 CFR Part 80, Subpart M (and Subpart E for biogas pathways). Part 80 is the operational engine of the RFS: it defines who is obligated to comply, how obligations are calculated, and the RIN credit system used for compliance trading.

Obligated parties and RVOs (§§ 80.1406–80.1407): The RFS obligates petroleum refiners and importers — not blenders or retailers. Each obligated party must demonstrate, for each annual compliance period, that it has met its Renewable Volume Obligation (RVO) — a volume of renewable fuel (measured in RINs) equal to the annual percentage standard × the party's volume of non-renewable gasoline and diesel produced or imported. For 2025, the standards are: cellulosic biofuel 0.81%, biomass-based diesel 3.15%, advanced biofuel 4.31%, total renewable fuel 13.13% of fuel volume (§ 80.1405 Table 1).

Renewable Identification Numbers (RINs) (§§ 80.1425–80.1429): The RFS compliance currency is the RIN — a unique numeric identifier generated when qualifying renewable fuel is produced or imported. Each gallon of ethanol generates one RIN (equivalence value 1.0); each gallon of biodiesel generates 1.5 RINs; non-ester renewable diesel 1.7 RINs (§ 80.1415). RINs are "attached" to renewable fuel (K=1) until separated from the fuel volume (K=2), at which point they become freely tradeable compliance instruments. Obligated parties that cannot blend enough renewable fuel themselves purchase separated RINs on the market to meet their RVO. The EPA's moderated transaction system (EMTS) tracks every RIN generation, transfer, and retirement.

Fuel pathway D codes (§ 80.1426): Each RIN carries a D code identifying which renewable fuel standard it satisfies: D3 (cellulosic biofuel — 60% GHG reduction required), D4 (biomass-based diesel — 50%), D5 (advanced biofuel from qualifying feedstocks — 50%), D6 (conventional renewable fuel, primarily corn ethanol — 20%). Obligated parties must accumulate the right mix of D codes to satisfy each of the four nested standards. A D3 RIN satisfies the cellulosic, advanced, and total renewable standards simultaneously; a D6 corn ethanol RIN satisfies only the total standard.

Biogas-derived renewable fuel (Subpart E, §§ 80.100–80.145): Subpart E governs RNG (renewable natural gas) from biogas — landfill gas, digester gas, and agricultural waste gas that is cleaned up to pipeline quality and used as vehicle fuel or electricity. Biogas producers must register with EPA (§ 80.105), track production with verified meters, and generate RINs through a specialized pathway. RNG-derived electricity used in electric vehicles earns eRINs — the newest addition to the RFS compliance toolkit.

Recent rulemakings: The RFS2 program (75 FR 14863, March 2010) established the four-category nested standards and D code system. Major updates include the Small Refinery Exemption reform (85 FR 78467, December 2020), the 2022-2025 volumes rule (88 FR 44586, June 2023), and a series of amendments published April 1, 2026 (91 FR 16487–16489) updating the annual standards table and RIN generation provisions for biogas pathways.

Implementing Regulations — Fuel and Additive Registration (40 CFR Part 79)

Before a fuel or fuel additive can be introduced into commerce, the manufacturer must register it with EPA under 40 CFR Part 79 — the pre-market registration program authorized by CAA § 211 (42 U.S.C. § 7545). This is a distinct requirement from Part 1090's composition standards: Part 1090 says what fuels must contain; Part 79 says who must register before selling fuels or additives and what information they must disclose.

• § 79.1 — Applicability: any manufacturer that introduces a fuel or fuel additive into commerce in the United States must register under Part 79; "manufacturer" includes domestic producers and importers; bulk purchasers who blend registered components are generally not separately obligated, but anyone reformulating a product to create a distinct fuel/additive must register that product
• § 79.10 — Fuel manufacturer registration: each fuel manufacturer must submit a registration with EPA identifying the fuel by chemical composition, the intended use (automotive gasoline, diesel, aviation, marine, etc.), and the geographic markets; separate registrations are required for meaningfully different formulations
• § 79.11 — Required registration information: registration submissions must include (1) the fuel or additive's chemical identity and composition, including concentration ranges for all intentionally added components, (2) the intended use and typical use conditions, (3) identification of any additives present above de minimis concentrations, and (4) existing toxicological and emissions data; EPA does not pre-approve the formulation — registration is a disclosure and tracking mechanism, not a safety certification
• § 79.12 — Noncompliance: introducing an unregistered fuel or additive into commerce is a violation of CAA § 211; EPA may issue compliance orders and assess civil penalties; registered products that are reformulated to an extent that creates a materially different product must be re-registered before the new formulation enters commerce
• § 79.13 — Registration issuance: EPA issues a registration number (and publishes registered products in a public database) once a complete submission is received; registration is not discretionary — EPA must register any product for which a complete submission is provided; the agency's tool is requiring complete information, not approval authority
• § 79.14 — Registration termination: a registration may be terminated if the manufacturer withdraws, if EPA finds the submission was materially false, or if the product is no longer introduced into commerce; a terminated product may not be re-introduced without a new registration
• § 79.20 — Additive manufacturer registration: fuel additives (detergents, deposit-control additives, oxygenates, lubricity improvers, anti-icing agents, dyes, markers) are registered separately from the fuels that carry them; the additive registration must identify chemical composition, function, treat rate range, and the fuels in which use is intended; Part 1090 references the Part 79 additive registry at § 1090.265 — only additives already registered under Part 79 may be included in gasoline covered by Part 1090

The Part 79 registry serves as EPA's visibility mechanism for the complex chemistry actually present in the commercial fuel supply. Thousands of distinct fuels and additives are registered — EPA uses the registry data to prioritize fuel/additive combinations for health-effects testing under CAA § 211(b), and enforcement agencies use it to verify that products at retail and bulk terminals are lawfully introduced into commerce.

Statutory Authority

This rule implements:

• 42 U.S.C. § 7545 — Regulation of fuels: authorizes EPA to control or prohibit manufacture, introduction into commerce, offering for sale, or sale of fuel or fuel additives; § 7545(c) authorizes testing requirements; § 7545(k) mandates the Reformulated Gasoline program for ozone-polluted areas; § 7545(o) established the Renewable Fuel Standard (which is implemented separately at 40 CFR Part 80 Subpart M and is not part of Part 1090)
• 42 U.S.C. § 7414 — Inspections, monitoring, and entry authority supporting EPA's enforcement of fuel quality standards

Recent Rulemakings

• 85 FR 78469 (December 29, 2020): Consolidation rule — brought together the Tier 3 gasoline sulfur standard (formerly at 40 CFR Part 80 Subpart O), ULSD rules, RFG program, and fuel additive provisions into the new 40 CFR Part 1090. Streamlined recordkeeping and reporting; standardized PTD requirements.
• 90 FR 4344–4367 (January 14, 2025): Multiple parallel amendments to Part 1090 updating technical test procedures, oxygenate standards, and ECA marine fuel provisions.
• 91 FR 16499 (April 1, 2026): Seasonal RVP standard update and related amendments to §§ 1090.300 and 1090.305 (diesel standards). Amendments to the summer RVP procedures and reinstating the 1.0 psi E10 allowance in qualifying areas.

Recent Developments

• E15 year-round sales expansion: EPA has been working to allow year-round sale of E15 (gasoline blended with 15% ethanol) in more markets. Under existing regulations, E15 sales are restricted during summer months (June 1–September 15) in most of the country due to RVP volatility concerns. A final rule extending the 1.0 psi waiver to E15 for summer months — allowing year-round E15 sales nationally — has been a priority for corn ethanol producers and the farm lobby. Partial RVP provisions were updated in the April 2026 Part 1090 amendment.
• Trump administration fuel economy and ethanol policy: The Trump administration has maintained support for corn ethanol blending requirements under the Renewable Fuel Standard (RFS) — a bipartisan priority given corn state political dynamics — while seeking to reduce other clean fuel mandates. The administration's energy deregulation agenda has focused more on oil and gas production than fuel quality standard rollbacks, leaving Part 1090's core framework largely intact.
• ULSD and sulfur enforcement: EPA continues enforcement of ultra-low sulfur diesel (ULSD, 15 ppm maximum sulfur) requirements throughout the fuel distribution system. Diesel sulfur violations — often resulting from contamination during blending or transport — remain an enforcement priority because high-sulfur diesel rapidly degrades catalytic converters and diesel particulate filters on modern heavy-duty engines. EPA's mobile source enforcement program tests fuel samples at terminals, truck stops, and retail locations.
• Marine fuel sulfur limits: International Maritime Organization (IMO) 2020 rules requiring ships to burn 0.5% sulfur fuel in most ocean areas took effect in January 2020. EPA's Part 1090 ECA marine fuel provisions (0.1% sulfur in Emission Control Areas including U.S. coastal waters) remain in effect, creating a differentiated marine fuel market. Monitoring and enforcement of ship fuel compliance is coordinated between EPA, Coast Guard, and port authorities.

Pending Action

(Left for wiki-enrich — Renewable Fuel Standard rulemaking (40 CFR Part 80) and E15 year-round sale rulemakings are proceeding separately.)