Against 381 other 4-cyl cars rated 2024–2026, the CT5 trails their 26.3 mpg average by 5.3 mpg, about $369 a year. Averaged over the years each was sold, the most economical engine since 2020, the 2L 4-cyl (2020–2026), does 26.4 mpg and the thirstiest, the 6.2L 8-cyl (2022–2026), 15.6: $1,007 a year apart.
Every Cadillac CT5 engine, compared
Yearly cost assumes 12,000 miles at $3.20 a gallon.
| Engine | Combined | City / Highway | Years | Fuel per year |
|---|---|---|---|---|
| 2L 4-cyl | 22.9 / 32.3 | 2020–2026 | $1,455 | |
| 3L 6-cyl | 19 / 27.3 | 2020–2026 | $1,753 | |
| 6.2L 8-cyl | 13 / 20.8 | 2022–2026 | $2,462 |
What that actually costs
Against its rivals in the same model years, the BMW M5 gets 14 mpg, the Kia K4 33.5 mpg and the Audi RS 7 16.5 mpg, next to 21 mpg for the 2026 CT5.
| Measure | Value |
|---|---|
| Cost per mile (2026) | $0.152 |
| Fuel per year | $1,829 |
| Fuel over five years | $9,145 |
| Against other 4-cyl cars, 2024–2026 | +$369 a year |
| EPA's own estimate | $3,668 a year |
City or highway — who is this car for
The 2026 Cadillac CT5 gives up 8.3 mpg in town: 26.3 on the highway against 18 in the city, $673 a year if every mile were city driving.
| Measure | Value | Reading |
|---|---|---|
| City (2026) | 18 mpg | $2,133 a year if you only drive in town |
| Highway | 26.3 mpg | $1,460 a year if you mostly commute |
| Gap | +8.3 mpg (46%) | Wide — this car dislikes traffic |
How the CT5 changed over the years
The CT5 peaked in 2021 at 24 mpg (21 city, 30 highway) and was at its thirstiest in 2026 at 21 — 3 mpg apart, or $229 a year in fuel between buying one year and the other. The 2026 car does 21.
| Model year | Combined | City / Highway | Engines offered | Fuel per year |
|---|---|---|---|---|
| 2026 | 18 / 26.3 | 3 | $1,829 | |
| 2025 | 18.3 / 26.7 | 3 | $1,829 | |
| 2024 | 18.3 / 27 | 3 | $1,770 | |
| 2023 | 18.3 / 27 | 3 | $1,770 | |
| 2022 | 18.3 / 27.3 | 3 | $1,770 | |
| 2021 | 21 / 30 | 2 | $1,600 | |
| 2020 | 21 / 29 | 2 | $1,634 |
MPG is a number. Dollars per year is the answer.
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How we count
This page rests on 19 EPA ratings of the Cadillac CT5 — 3 engines across 2020–2026. The mileage is EPA's laboratory figure, unchanged; the yearly bill is ours, at 12,000 miles and $3.20 a gallon, against EPA's own estimate of $3,668. Full method.
Frequently asked questions
What mpg does the 2026 Cadillac CT5 get?
21 mpg combined, 18 city and 26.3 highway, per EPA; its 3 versions that year range from 15 to 26. Across every year since 2020 the CT5 has averaged 21.9 mpg.
Is the 2026 CT5 more efficient than the 2025?
About the same: 21 against 21 mpg combined.
Which CT5 year has the best gas mileage?
The 2021, at 24 mpg combined (21 city, 30 highway).
Does the CT5 get better gas mileage than the BMW M5?
Yes: 21 mpg for the 2026 CT5 against 14 for the 2026 BMW M5, about $914 a year less to run.
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