hello everyone, i have been shifting very early with my car. I've been shifting In such a way that i land in 1k rpm, which is at 1300 I'm 4th and 5th.

It seems fine to be but I can't be sure. I don't know if the engine actually lugs because I don't know how to recognise. i never let it drop below 1k (unless when in neutral cause it idles at 750), so my question is when is it lugging and is this the best way to shift to conserve my fuel?

I've noticed that if I let it stall with the clutch it still "runs" a lot lower than 750rpm. Accelerating slowly from 1k makes a low hum, kind of sound. doesn't seem like lugging to me but then again I don't know. Can anyone help me out? thanks.

PS: I have measured my mpg with this shifting method over 160km, and I got 7L/100km, which more efficient than anything I've ever had.