An Austrian dude named the Mercedes line of cars after his daughter Mercédès Adrienne Ramona Manuela Jellinek. He got the name from Spanish, and in Spanish all the "e"s are pronounced the same
Well, in Spanish none of the "e"s in "Mercedes" have an accent mark in them, and in Spanish the accent mark only flags the tonic syllable, it doesn't change the pronunciation.
So no.
That's how you spell that name in French, though. And yes, you do say all those the same there, too.
Except that the name written in Spanish does not have any accent markings, and even if it did, it would not change the pronunciation of the letter. Accent markings over vowels in Spanish simply denote syllable stress.