I have just purchased a Mercedes R class 2007 with 90000 miles. Looks like all regular work was kept up but can you tell me what I could be looking to have to replace anytime soon. Tires are good and having brakes and new rotors put on before I take it off lot. Is it ok to use regular gasoline?
C M B

Regular gasoline? Read the manual, look on the dash, look on the inside of gas cover.....it tells you what type of fuel to use. With 90k, you should just do the full 90k service as specified by the manual. You are given 30,k, 60k, and 90k. Take care of everything now and that way you can establish a baseline. CHEERS! and welcome to the forum.

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1990 190E 3.0L

what type of motor do you have?does your transmission need service?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran

I'm pretty sure there is a fed regulation that every modern car made has to " run" on 87 regular. ( computer equiped cars with knock sensors not older non computer cars )

I ran my 97 SL320 M104 straight 6 on mid grade for a while then moved to 91, there was a difference in the sharpness of the engine when the switch was made.

If you drive on level ground at 40 ish MPH regular would probably be just fine.

Also see
Regular or Premium? - Feature - Car and Driver

Just because something will "run" on a fuel doesn't mean it's appropriate, true? By analogy, your body can "run" on burgers, fries and shakes, but you're not going to be as healthy ("run as well") or live as long as if you eat a balanced diet.

OP: your engine was DESIGNED for premium fuel. This isn't an issue of the knock sensor compensating, either. Yes, it will run on regular (as noted, read the manual...), but you'll be doing long-term damage to the engine and exhaust components -- and cats cost a lot more than the difference in fuel for a few hundred tanks of gas.

Good luck.