Bob, yes,I agree that the numbers don't fully support HCH 2 drivers being more committed FE drivers than Prius 2 drivers. Now there is a hint of support there in the higher number of above average mpg drivers(median a little higher than mean), and in CR's numbers for both vehicles.If we assume that CR's drivers just drive to the specs of their test, then we do have to ask why their city loop for the HCH 2 was just 26 mpg(just 55% of our posters numbers) while out HCH 2 drivers get ~47mpg. CRs city loop with the Prius 2 was 35 mpg(73%) vs the 48 mpg we get here.
Another possible explanation is that HCH 2 drivers(here, on this forum)) might do more hy driving,and less city driving, than Prius drivers(forum drivers/posters).
If I get a bit more time,and have even less of a real life, I might sample some HCH 2 drivers post count vs Prius 2 post counts. Prius 2 counts should be a lot higher since they have been out since ~2004. I should probably do post counts per unit of time(months maybe) to control a bit for time.
On to the subject you are interested in which I'll paraphrase as "why does the Prius 2-a heavier, faster , bigger car-get better mpg than the Prius 1."
Do you have the relevant #s posted in any single place:
1)Weight
2) 0-60 1/4 mile
3)Claimed hp for ICE
4)Claimed HP for electrical motors
5)Total max storage capacity in watt hr for the 2 vehicles.
6) How much the batteries can be drained? 70%
7) Max "regen" energy pre 5 minutes.The Prius 2 manual says 200 watt-Hr per 5 minutes is the most it can display.I'n not sure that is the actual max it can regen, but maybe it is.
Have you been able to figure out how much of the Prius's 1 or 2 regen braking is actually from real "hitting the brake pedal braking", as opposed to the Prius's computer deciding to add subtle braking when the driver rolls off the gas, but doesn't hit the brake pedal??
I would be willing to bet that Toyota added more of this "unasked for braking" to the Prius 2. How else could they supply the extra electrical energy that the Prius 2 must use?
My 1st thought is that this " unasked for braking"would require a bigger program that would take more memory(of whatever type of memory this would need), and you could check memory "size' of the Prius 1 vs Prius 2. On second thought, this might not be so.Maybe Toyota just did something simple like" add regen braking whenever the pedal changes position 20% instead of 30%". A command like this wouldn't take any more memory. Besides , the memory of all vehicles increases with each new model; it would be impossible to make anything out of an increase in memory of program size. We couldn't/can't assume that it is for my pet idea.
Do you have any idea on how we can measure regen. on the Prius 1 and Prius 2(per unit of time or distance on a set course)?
Do you have any idea on how to measure electrical energy used(per unit of time or distance-on a "set" drive of course, by the electrical motors on the Prius 1 vs Prius 2??
It is possible-maybe likely-that the Prius 2 actually has more efficient ICE , electrical motors, lower aero drag,lower rolling resistance, lower drivetrain losses(better bearings, thinner grease,lower vis oil). Toyota also might have increased the amount of energy it could regen during hard stops that required both types of "brakes"-use electrical braking instead of friction braking???I still think that some of the improvement is due to more unasked for brake regen.Bigger, more powerful electrical motors/gens should be able to brake harder-right?
The downside of doing more unasked for brake regen is obvious-if Toyota added more braking in situations where the driver doesn't need more braking, then it would actually hurt efficiency because the driver is going to have to use more energy to get that speed back. I would bet Toyota has a program that predicts when a roll off throttle indicates that braking will very likely be needed. The computer then " works faster than the human" and adds braking. I wonder if Toyota could/did access this info from Prius 1's when they did maintenance on them? Toyota might have used this real world info to improve the regen brake program on the Prius 2??
Hmmm,I'm running on.Sorry.Thanks,Charlie