Is it a driving technique regardless of mpg or a driving technique that leads to high MPG, and if its about high MPG, what MPG would it take to be considered hypermilling on a gen 2?
There are varying degrees and techniques when it comes to "hypermiling". Most people do one or two relatively simple things (easy on the accelerator, off the gas well before a red light, avoid passing gear, responsibly use the "pulse and glide" method, etc.) that are mild forms of hypermiling. Some people go as far as altering their car's body to reduce drag, "pulse and glide" without regard to others on the road, and s other more extreme measures. I don't think you can really define what exactly constitutes hypermiling or put an mpg figure on it any more. I just take it easy, don't drive aggressively, stay mostly in the right lane and don't agonize about it. Life's too short. Just enjoy the drive.
To me, there are two tests involved in defining a particular episode of driving as "hypermiling." 1. Improved MPG over EPA baseline, without any further specificity 2. The driving style does not particularly honor momentary traffic or regulatory norms, e.g. operating well below the applicable speed limit in the presence of public traffic. In other words, if other drivers can tell that you aren't just trying to get from A to B and you also happen to get a better MPG score than usual, that's hypermiling in my book.
Not exactly hypermiling, by any stretch, but anyway: reducing your overall use of the car. Some ploys: 1. Walk for short distance errands. Or bicycle? 2. Consolidating errands into one trip, when practical. 3. When there are optional destinations, choose the one closest. A big box mega-store you need to drive to, vs small but local, for example. 4. Take transit occasionally, for example downtown events, where traffic will be bad and parking costly. 5. Got a tedious daily commute? Consider taking transit.
So the government says the combined is 46, Im getting 55 on the MFD, maybe 54 when hand calculated. I feel like thats good but not crazy good? I guess when you consider its a 12+ year old vehicle thats darn good, is it hypermiling? I feel like I can still push 50 MPG without even trying. Im feel limited by my commute as well, maybe its not a hypermile friendly commute.
Generally a Prius will struggle to score top MPG at higher speeds. If you can avoid fast freeway runs you'll do better.
If you are getting 50 MPG (US) or better, you are doing well in my books. 54–55 MPG is pretty good going for a Gen 2 IMO.
IMO..not the only or exclusive aspect of hypermiling techniques, but the two main aspects are: #1, Planning ahead, either before the actual trip, or during the actual drive-or both, to facilitate a route and/or make driving choices that allow for utilizing momentum and glide for the highest MPG returns. During the drive, this would be gliding or rolling to stops, stop signs, and simply trying to get from point A to point B, with as little gasoline powered acceleration as possible. Pre-evaluation of upcoming inclines and descents, and using both to the best of advantage. #2. Big technique. Pulse and Glide. Which IMO is simply reaching speed, then gliding as much as safely is possible, then pulsing back up to speed. To be honest, I never used Pulse and Glide because I found it too distracting to try to maintain for any long period. Potentially unsafe, and annoying to others driving around me. That being said. Now that I don't own a Prius, I have found that IF I drive my ICE Honda Fit, with the "Prius" mindset, ( See #1 )...it's pretty impressive how much I can impact the MPG of my non-Hybrid vehicle.
Under Uncle Wayne's definition, it is not one single driving technique, but a broad menu of techniques and choices and adjustments, pick as many or few as reasonably fit your situation. Anything that beats the EPA rating is a success, though the EPA rating scale was a somewhat higher bar back then. EPA's scale has undergone repeated adjustments, always in the direction of acknowledging the modern cultural realities of higher speeds, more aggressive driving habits, and increased congestions that reduce real world MPGs.