Mercedes-Benz 420SEL
15 MPG The 1991 Mercedes-Benz 420SEL is EPA-rated at 15 MPG combined (14 city / 17 highway). Over 15,000 miles a year that is about 1000 gallons, $3200 a year in fuel, or $0.213 per mile at $3.20/gal.
Across its full 1986–1991 run it averages 15 MPG, essentially flat across 6 model years.
Running cost at different fuel prices and mileages
The figure everyone actually wants, and the one the EPA does not publish — because it depends on a fuel price no agency will commit to.
| Fuel price | Per mile | 10,000 mi/yr | 15,000 mi/yr | 20,000 mi/yr |
|---|---|---|---|---|
| $2.50/gal | $0.167 | $1667 | $2500 | $3333 |
| $3.00/gal | $0.200 | $2000 | $3000 | $4000 |
| $3.20/gal | $0.213 | $2133 | $3200 | $4267 |
| $3.50/gal | $0.233 | $2333 | $3500 | $4667 |
| $4.00/gal | $0.267 | $2667 | $4000 | $5333 |
| $4.50/gal | $0.300 | $3000 | $4500 | $6000 |
| $5.00/gal | $0.333 | $3333 | $5000 | $6667 |
Every model year
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 1991 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
| 1990 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
| 1989 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
| 1988 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
| 1987 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
| 1986 | 15 MPG | 14 | 17 | $5150 | 592 | 1 |
Where a model year offered several engines or drivetrains, the figure is the average across all EPA-tested trims that year — the trim count is shown so you can see how much averaging is involved.
How it compares in its class
Among the 261 midsize cars models tracked here, the Mercedes-Benz 420SEL ranks 250 on current figures, against a class average of 27.3 MPG.
Closest more-efficient alternatives in the same class: Audi RS 7 (16), Cadillac CTS-V (16), Dodge Challenger SRT (16), Infiniti Q45 Full-Active Suspension (16), Mercedes-Benz E55 AMG (16).
Tailpipe CO₂ is rated at 592 grams per mile, which works out to roughly 8.9 tonnes a year at 15,000 miles.
Questions
What MPG does the Mercedes-Benz 420SEL get?
The 1991 Mercedes-Benz 420SEL is rated at 15 MPG combined by the EPA — 14 city and 17 highway. Across all 6 model years in the database it averages 15 MPG, ranging from 15 to 15 depending on year and trim.
How much does a Mercedes-Benz 420SEL cost in fuel per year?
At 15 MPG and 15,000 miles a year, it burns about 1000 gallons — roughly $3200 a year with fuel at $3.20 a gallon, or $0.213 per mile. The EPA's own published annual figure for the 1991 model is $5150.
Has the Mercedes-Benz 420SEL become more efficient over time?
Barely. It sits at 15 MPG today against 15 in 1986 — essentially flat across 6 model years, with efficiency gains offset by weight and power creep.
Is the Mercedes-Benz 420SEL efficient for its class?
It ranks 250 of 261 in the Midsize Cars class on current figures, against a class average of 27.3 MPG. That is 12.3 worse than typical for the class.
EPA test figures from fueleconomy.gov. Cost per mile and annual fuel spend are computed at a reference price of $3.20 per gallon — use your own price. Estimates based on official test figures and average fuel prices. Real-world consumption varies with driving style, load, terrain and maintenance.