1994 Sc300 Highway Rpm?

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Hey everyone. I just bought my ride so I'm new to the forum. I noticed that it gets up to 3k when I hit 70 mph and was wandering if that's normal. When I go 80 it gets up to 3.5k. I called my mechanic buddy and he said it's probably b/c it's a high performance vehicle. Is he right? It seems high to me because my other car is in the 2.5k range at 70. I know a lot of factors probably go into the RPM but I assume this probably affects the gas mileage.

What kinds of ranges do you all see? Do I have a problem?

Thanks a lot