GMC · 1989–2026 · Diesel
GMC Sierra Diesel MPG by year
The EPA has rated 17 model years of the GMC Sierra Diesel, from 1989 to 2026. The most fuel-efficient year is the 2025, at 26 MPG combined in its best configuration. The best 2026 model is 32% more efficient than the best 1989 model (25 vs. 19 MPG). The 2026 model is 19% more efficient than the median full-size pickup that year (25 vs. 21 MPG).
Combined MPG by model year
- Sierra Diesel, most efficient version
- Range across configurations
- Class median
Shaded band: range across that year's configurations. Class median: same-year models in the same class, rated in MPG. Click a point to open that model year; the table below lists every value.
Every Sierra Diesel model year
| Year | Type | Best combined | City / Hwy | Class median | Range | Configs | Fuel / yr |
|---|---|---|---|---|---|---|---|
| 2026 | Diesel | 25 MPG lowest 19 |
23 / 28 | 21 | — | 4 | $2,220 |
| 2025 | Diesel | 26 MPG lowest 19 |
23 / 29 | 21 | — | 4 | $2,135 |
| 2024 | Diesel | 25 MPG lowest 19 |
23 / 29 | 21 | — | 4 | $2,220 |
| 2023 | Diesel | 26 MPG lowest 22 |
24 / 29 | 22 | — | 3 | $2,135 |
| 2022 | Diesel | 26 MPG lowest 21 |
23 / 30 | 22 | — | 3 | $2,135 |
| 2021 | Diesel | 26 MPG lowest 24 |
23 / 30 | 22 | — | 2 | $2,135 |
| 2020 | Diesel | 26 MPG lowest 24 |
23 / 30 | 21.5 | — | 2 | $2,135 |
| 1998 | Diesel | 15 MPG | 13 / 17 | 16 | — | 2 | $3,700 |
| 1997 | Diesel | 15 MPG | 14 / 17 | 17 | — | 2 | $3,700 |
| 1996 | Diesel | 16 MPG lowest 15 |
15 / 19 | 16 | — | 3 | $3,469 |
| 1995 | Diesel | 19 MPG lowest 14 |
17 / 22 | 18 | — | 8 | $2,921 |
| 1994 | Diesel | 19 MPG lowest 15 |
17 / 22 | 18 | — | 10 | $2,921 |
| 1993 | Diesel | 18 MPG lowest 17 |
16 / 21 | 17 | — | 5 | $3,083 |
| 1992 | Diesel | 20 MPG lowest 17 |
18 / 23 | 18 | — | 4 | $2,775 |
| 1991 | Diesel | 20 MPG lowest 16 |
18 / 23 | 17 | — | 7 | $2,775 |
| 1990 | Diesel | 18 MPG lowest 16 |
16 / 22 | 17 | — | 4 | $3,083 |
| 1989 | Diesel | 19 MPG lowest 16 |
17 / 23 | 17 | — | 4 | $2,921 |
Fuel cost uses today's default prices for every year so model years compare like for like. Sort any column.
Compare Sierra Diesel model years
See how much a newer Sierra Diesel would save over an older one.
Models similar to the GMC Sierra Diesel
Other GMC Sierra versions
Frequently asked questions
Which GMC Sierra Diesel year has the best fuel economy?
The 2020 GMC Sierra Diesel, rated up to 26 MPG combined. At 15,000 miles a year with $3.70/gal diesel fuel, that works out to about $2,135 a year.
Which GMC Sierra Diesel year has the worst fuel economy?
The 1997 model, whose most efficient version is rated 15 MPG combined (about $3,700 a year to fuel).
What is the fuel economy of the latest GMC Sierra Diesel?
The 2026 GMC Sierra Diesel is rated up to 25 MPG combined.