Mercedes-Benz Flex Fuel Vehicles
Mercedes-Benz is the most flex-fuel-prolific European brand to sell in the United States. From 2003 through 2019, Mercedes offered FFV variants across the C-Class, E-Class, ML/GLE, CLA, and GLA model lines, most commonly with the 3.5L V6 but also with the 2.0L turbo four-cylinder in CLA250 and GLA250 4MATIC models. The brand marketed these vehicles as "Flexible Fuel Vehicles" on MBUSA.com, though FFV availability was not universal across every dealer or state — buyers had to confirm with MBUSA or dealer inventory at the time.
Verification today relies on the distinctive black fuel cap with a yellow outer ring and a filler-door label reading "Premium Gasoline (min 91 Octane) or E85 Only." Unlike most American FFVs, Mercedes FFVs do not accept regular 87-octane gasoline — it's premium or E85 only.
Mercedes-Benz flex fuel models
| Model | Year range | Engine | Notes |
|---|---|---|---|
| C320 (W203) | 2003–2005 | 3.2L V6 | Luxury/Sport/Wagon |
| C240 (W203) | 2005 | 2.6L V6 | |
| C230 (W203) | 2007 | 2.5L V6 | |
| C300 (W204) | 2008–2012 | 3.0L V6 | |
| C350 / C300 (W204) | 2012–2014 | 3.5L V6 | |
| E350 (W212) | 2012–2016 | 3.5L V6 | Sedan/Coupe/Cabriolet |
| ML350 (W166) | 2012–2015 | 3.5L V6 | |
| GLE350 | 2016–2018 | 3.5L V6 | |
| CLA250 4MATIC | 2015–2019 | 2.0L turbo I4 | |
| GLA250 4MATIC | 2015–2019 | 2.0L turbo I4 | |
| GLA350 4MATIC | 2016–2018 | 3.5L V6 |
Mercedes-Benz-specific E85 tips
Premium or E85 — not regular.
The fuel-door label is unambiguous: Mercedes FFVs require minimum 91-octane gasoline when running on gas, or E85 when running on ethanol. Regular 87-octane is not approved.
Verify via the yellow-ringed fuel cap.
Mercedes did not install yellow fuel caps across the board — the FFV convention uses a black cap with a yellow outer ring. Combined with the filler-door label, this is the clearest visual confirmation.
Mileage drops noticeably on E85.
Owners commonly report roughly 5 mpg less on highway runs with E85 versus premium gasoline, plus longer cold-start heater warm-up times in winter.
Not every C-Class or E-Class is an FFV.
Engine, model year, and original state of sale all matter. VIN decoding and a dealer lookup are the safest path to confirmation.
Other flex-fuel brands
Find E85 Near You
Your Mercedes-Benz FFV deserves the cheapest pump. Use the live map to find it.
Open E85 locator →Best E85 Vehicles of 2026
Our 2026 buyer's guide covers which FFVs make sense used vs. new, plus per-mile cost math.
Read the guide →