Charlie, I don't have an aftermarket PHEV (or any variety of such), but could you imagine the damage I could do if I DID have one? Wow! Realize, that despite this tank reading 70.0 mpg, the hand calculated value was 66.4 mpg (my display is about 6% optimistic). As far as getting that kind of mileage, it is a combination of driving habits, commute, weather, and luck. Driving habits include - keeping top speed below 60 mph, tires inflated to max PSI, and not tailgating so I can anticipate stops. Commute - I have an approximate 35 mile, one way commute, so the lousy gas mileage I get on the first 5 minutes (30 mpg for 2 miles) during warmup, is minimized by another 45 minutes of gas mileage (60+) once the engine is warm. Also, I will hit a stretch of slow and go for about 5 miles during my normal commute. This gives me an opportunity to pulse and glide and improve the overall tank. Weather - This was done when the weather was very warm and dry. I managed to keep the car cool during the day (parking in shade) and then just running the vent to keep my cool while driving, rather than the A/C. A bit extreme, but I was going for a record tank. Lastly, luck. There were a couple of accidents that occurred during my commute, that when I got there, the accident had cleared. However, it impacted traffic by slowing it down for stretches of a few miles. These reduced speeds allowed for more pulse and gliding as well as reduced speed driving which allows for great MPG's.