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I am living in France and own a C43 AMG from end 2018 (390HP engine). The fuel has become very expensive, 90% of the price is Government taxes that are killing us and this is the reason why I am thinking about going for an engine tune to be able to have Flex Fuel : regular gas which is called SP98 here and Ethanol which is E85. The tune cost around 400$ and it does not increase the engine power, only allow to use Ethanol as fuel.
The fact of the matter is that is quite complicated to get the truth about E85 here because it seems like Government does not want to see many people switch to a cheaper option. Thus, I wanted to check with MB owners from other countries with eventually non biaised point of views.
Therefore my question is, is it risky for my engine to do such thing ? I am also considering doing 70% E85 and 30% regular Gas eventually, I will never try it without going through a reprog first.
You cannot run more than about e30 without upgrading the LPFP, HPFP, fuel rail and a custom tune (ie not an off the shelf tune for $400) to run higher ethanol content. It can be done, but you are looking at $5,000 to $7,000 USD for parts, labor and dyno time.
Specifically, ethanol can result in serious fuel system corrosion if the engine is not designed for it. It's not just a tune as said above. AMG actually specifically states never to refuel with gasoline with more than 10% ethanol. These engines from the factory are suitable for up to E10 only. A tune can allow for more w/o getting the CEL, but that won't protect against corrosion.
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