'78 280 SL High RPM's
 

I have a '78 280 SL that revs at about 4000 RPM's at 110 KPH. Is that right? Seems like I should have another "overdrive" gear to drop into, but stays high. Is this normal? Is it just the gear ratio?

Thanks.

Gearing is the way MB gets away with propelling a 3500lb auto with a 160 cubic inch motor and still call it a sportscar.

What you get down low can only be replaced up high with another gear. Since the engine has a 6000 redline (or so), you still should be able to go top speed which I would guess is almost 130.