[Telemachos]

I've been musing about the benefits and drawbacks of P&G (which I am new to) and it occurred to me that I might not be seeing its full effect, if any, due to the lack of critical information about my car.

As I have understood it, the benefit of P&G is that you maximise the amount of time that the engine is operating in its most fuel efficient "zone" and coast for the rest of the time. I've managed to glean that the engine FE (or Brake Specific Fuel Consumption (BSFC)) is dependent on the engine RPM and output torque as it is related to optimum engine temps and frictions I'm assuming. This gives me only the engine RPM to control the FE from the driver's seat at any given driving speed and condition, hence the "revving up" to desired RPM and then gliding.

So that brings me to the question: Isn't it a prerequisite that I know where my car has its optimum RPM for any given torque load, i.e the BSFC map, and won't I just be winging it without that information? I've found that the i10 has its max torque at 4500 RPM, but this doesn't necessarily mean its peak FE is there right?

Can anyone clarify this? Am I better just going for constant low speed/ high gear instead?

PS: If anyone has a BSFC map for a Hyundai i10 (2011) that would be grand!