70mph freeway

why do you find it difficult? the slower you go, the better the mpg's. what do you mean by sweet spot?

 

A better sweet spot, 50-55mph, but not on freeway! You will be run over or?

 

The sweet spot on any road is to go as slow as you can (down to 15 mph) without endangering yourself or others or pissing people off. The latter one is the hardest considering some people will find about any excuse to be pissed off.

 

What's difficult about 70mph? I find the Prius is more than capable through its entire speed range up to 115mph. No gears means there should be no difficulties you would have in other standard automatic transmission cars where it is constantly hunting to find the correct ratio.

 

If you are implying that you have to near floor it to maintain 70 mph then something is wrong with your car.

But you should probably average around 50 mpg at that speed. That's more of a guess. There's more qualified people on here that can give you a little more exact number.

 

My work commute is 80% highway and to stay in EV mode, it's 63 or less. When not in EV mode, it's the speed limit or a few miles under. I take advantage of EV mode every opportunity so I'm not really concerned with overall mileage, but I do drive conservatively. When I drive my other car (non hybrid) I also conserve fuel by driving a few MPH under the speed limit. My newly acquired habit. I don't impede the flow of traffic.

 

My PIP's MPG on the motorways (yes thats what its called over the pond) at 70 MPH and thereabouts is 73. with the AC on.

 

If you are using US mph and mpg then that number is not anywhere close to possible, friend. Sorry.

 

Multiply by 0.83 to convert to mpg US, and it is about 61mpg. That is perfectly plausible with the PiP assuming you have enough charge in the main battery. The better question is what sort of fuel economy can you expect at 70mpg on the freeway/motorway when your extended pack is depleted so that it behaves as a standard GenIII Prius.

The answer is 53mpg to 50mpg in miles per US gallon when travelling around 70mph and filling up with 89 octane E10 fuel in mild clear weather.

Chart courtesy of Bob Wilson:

 

The rule I had in my Honda civic hybrid was 5 mpg less for every 5 miles over the speed limit (65 mph).

The pip gets about 55-60 mpg at 65 mph. So 45-50 mpg at 70, 40-45 at 75... And so on.

With EV boost you can minimize those effects but lose EV range on surface streets.


iPad ? HD

 

Linear relationships like "delta 5mpg/5mph" are doomed to fail because the increase in wind resistance/drag is a nonlinear effect. This only works on a very limited speed range, and not true for the GenIII Prius with the 1.8

 

I think "rule of thumb" type statements like chesleyn was doing is appropriate and very helpful to a person new to the Prius like the OP seems to be. They can always learn the more advanced stuff later.

 

Noted


iPad ? HD

 

Thats right on. I just completed a 400 mile all expressway trip. Drove whatever the traffic would allow, 65-70 or so. Ave 58mpg.

 

Op is having a hard time to keep the speed at 70 or below because he has a lead foot.

 

Just thought of something. Are you driving in ECO mode? If so, the pedal pressure is remapped to make the car lethargic unless you floor it and then you have all the power. Drive in normal mode, the only difference is the mapping of pedal pressure.

 

I think I can sympathize. If the terrain's relatively flat I use the cruise control more with his vehicle because for some reason it's harder to keep the speed from drifting (usually higher) than has been the case with my conventional cars. ECO mode probably exacerbates this effect but Normal mode is a little tricky too.

 

It is with the Imperial Gallon.