2021 Jeep Gladiator Rubicon EcoDiesel 4WD MPG & Specs — Real-World vs EPA, All Trims
Fuel grade varies by trim — see the breakdown below.
Is the 2021 Jeep Gladiator Rubicon EcoDiesel 4WD good on gas?
At up to 24 MPG combined, the 2021 Jeep Gladiator Rubicon EcoDiesel 4WD is better than average for a Standard Pickup Trucks 4WD — that class averages about 16.5 MPG across 1,581 EPA-tested versions, so it's a good pick on fuel for its size.
Real-world MPG vs the EPA number
The EPA figures above come from a standardized dynamometer test, not the open road — real-world MPG typically runs a bit lower depending on your driving, climate and terrain. That's true of every car on this site, old or new.
At today's AAA national average price — $4.78/gal for diesel gas as of 2026-07-05 — the most efficient trim runs about $2,988/year (roughly $249/month, about $19.92 per 100 miles) at the EPA's assumed 15,000 miles/year, using an estimated 625 gallons a year. We don't estimate a cost-per-fill since exact tank size isn't in the public EPA dataset, but the per-100-mile figure scales to any tank. Current national average gas prices →
2021 Jeep Gladiator Rubicon EcoDiesel 4WD trims & fuel economy
| Trim (engine / transmission) | Fuel | MPG | Fuel/yr (today's price) |
|---|---|---|---|
| 3.0L 6-cyl, Automatic 8-spd, 4WD | DIESEL | 24 | $2,988 |
2021 Jeep Gladiator Rubicon EcoDiesel 4WD specs
What the EPA test-car listings record for this model year — every combination sold is a row in the trims table above.
| Engine options | 3.0L 6-cyl turbo |
| Transmission | Automatic 8-spd |
| Drive type | 4WD |
| EPA body class | Standard Pickup Trucks 4WD |
| Fuel | Diesel |
| Tailpipe CO₂ | 436 g/mi |
Similar cars (Standard Pickup Trucks 4WD)
Cars that take premium · Cheapest cars to fuel · Where fuel grade depends on the trim · Fuel guides
1 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.