Fire it up, put it in gear, and step on the accelerator. Cruising at 65mph, you should be seeing roughly 2000rpm. When accelerating, 5700rpm will give you optimal torque. Keep the fluids changed at proper intervals and don't be always running it in the higher end of the RPM range, and you'll be fine. Revving it up as needed to get moving won't hurt it as long as all the fluids are in their proper places, but keeping it in high RPM all the time probably won't help it last.
Thanks for the reply, but I didn't really ask about that. I'll try to explain what's going on.
I used to drive a Mercedes, engine speed from 2000-2500 RPM. At the same time, the speed of movement is 45-55 MPH. I drove my wife's jeep at the same speed but at a higher speed in the range of 70-75MPH.
After I moved to an old car ("Moskvich 2140" 1987 release), I learned to drive slowly. Now, even in my wife's jeep, I drive at speeds up to 50 MPH and the engine speed does not exceed 1800 - 1900 RPM.
Is it bad for the engine to run at that speed?
These engines were designed to maximize fuel economy. That's why the RPMs are so low. The engine is certainly capable of running up to the redline, but as @RossoRacer said, running at high RPMs all the time will shorten the engine life. Let the ECM do what it wants to.