Another thing to note: If you were to run your engine in the horsepower range, which is around 4500 to 5000 RPM, the engine would be screaming all the time. Regular driving means the engine operates between about 600 RPM (idle) and 3000 RPM with the maximum torque being produced at about 2500 RPM. So torque is more important than horsepower. (My old Chevy, with a 350” engine and automatic transmission, would upshift under full throttle at 5000 RPM, or first to second gear shift @ 30 MPH and second to third gear shift @ 90 MPH.)
OLD cars had in-line 6 cylinder or in-line 8 cylinder engines. Because the crankshaft is longer and heavier, an in-line engine has more torque that a V6 or V8 engine.
Big Diesel engines idle at about 600 RPM with a maximum no-load RPM of maybe 2000 RPM. They run between 1400 to 1900 RPM when working.