Our '90 Mazda MPV with the 2.6 litre inline 4 and 5-speed MT ran at 2500 RPM at 100 KPH (62 MPH). It seemed happy there, and turned in good mileage.
The '09 Mazda5 with 2.3 l/5MT runs at about 2700 RPM @ 100 KPH, and again seems happy and is easy on fuel.
Can't remember the particulars for the '85 626, and my earlier cars didn't have a tach.
Toyota claimed, quite a few years ago, that an engine ran most efficiently at about 50% of redline, and geared its cars accordingly during the 55 MPH federal speed limit.
The '09 Mazda5 with 2.3 l/5MT runs at about 2700 RPM @ 100 KPH, and again seems happy and is easy on fuel.
Can't remember the particulars for the '85 626, and my earlier cars didn't have a tach.
Toyota claimed, quite a few years ago, that an engine ran most efficiently at about 50% of redline, and geared its cars accordingly during the 55 MPH federal speed limit.