When accelerating, even if you hold the accelerator in the same position, the engine rpms will rise as the car gains speed. With the goal of having the engine in the most efficient RPM range, is it best to let the rpms rise, or is it best to compensate by releasing a bit to try and keep the rpm the same?
I try to keep RPM below about 2400, above which efficiency drops, except when I have to have it higher -- e.g., merging onto a highway (which I drive very infrequently) or to climb a steep hill. For the latter, I try to minimize the need to push it higher by getting a running start before the climb and let speed decay as I approach the crest (while keeping things safe and legal). You may ask, how to know RPM without a tach? Keep instantaneous MPG above half the vehicle speed during acceleration and you should be below 2400 at most speeds. See this for more.
JimboK's advice to hold the MPH at ~ 1.6 - 2.0 fold of the current MPG number will help you increase your efficiency to a large extent without additional instrumentation as it did for me. January 11 - May 31 MFD MPG: 49.9 Driven Miles 5,000
