Why Is My Challenger Getting Bad Gas Mileage? Diagnosis Guide

What to Expect as Normal

Factory fuel economy ratings for the 2022 Challenger:

• V6 SXT/GT: 19 city / 30 highway / 23 combined
• R/T 5.7L auto: 16 city / 25 highway / 19 combined
• Scat Pack 6.4L auto: 15 city / 23 highway / 18 combined
• Hellcat auto: 13 city / 22 highway / 16 combined

Real-world experience is typically 1–3 MPG below EPA estimates in city driving and close to or matching EPA for steady highway cruising.

If you're significantly below these numbers (more than 3–4 MPG), something is contributing to excessive fuel consumption.

Most Common Causes

Driving style and conditions: The most obvious but often overlooked. The HEMI's fuel consumption is extremely sensitive to throttle input. City stop-and-go driving in Normal mode with the heavy 3,800+ lb car is hard on economy. Lots of short trips (engine never reaches full temperature) waste fuel during the cold warm-up period.

MDS not activating: In Normal mode, the 8-speed auto should activate MDS at highway cruise. If it's not (check the EVIC display for cylinder count), a fault with the MDS system or a tune that disables it costs 10–15% highway economy.

Tire pressure: Under-inflated tires increase rolling resistance. Check and inflate to door spec. Often ignored but real — 10 PSI low on all four tires costs 1–2 MPG.

Air filter condition: A severely clogged air filter restricts airflow, forcing the engine to work harder. Check and replace if it's been more than 25,000–30,000 miles.

O2 sensor malfunction: A failing O2 sensor can cause the PCM to run rich continuously (thinking the mixture is too lean). Check for related fault codes (P0131, P0134, P0151, etc.).

Fuel injector leak: A dripping injector adds unintended fuel. Symptoms include rich smell at startup, fouled spark plugs on specific cylinders.

Coolant temperature sensor failure: If the PCM thinks the engine is always cold, it runs the cold-start enrichment strategy indefinitely — dramatically rich conditions. Check for fault codes related to coolant temperature.

Spark plug condition: Worn spark plugs misfire occasionally — unburned fuel exits through the exhaust. Check plug condition at the recommended interval.

Thermostat stuck open: Engine never reaches proper operating temperature. The PCM runs enriched until the engine warms up — a stuck-open thermostat means it never does. Coolant temp gauge will read lower than normal.

A Tune's Effect on Economy

A conservative tune on 93 octane can slightly improve fuel economy (better combustion efficiency) while boosting power. An aggressive tune can reduce economy by 1–3 MPG if it keeps the engine out of MDS mode or runs richer mixtures throughout. Ask your tuner what effect the calibration has on cruise economy.