My 39mph "secret" for good gas mileage

I have found that also to be true.. I had the unfortunate luxury of driving between 37 and 45 on the highway!! (Was behind my inlaws car which only had 2nd gear)

I did approx 50 miles like that and averaged about 80MPG it was great.. I would love to do that all the time.. but.. I did almost get rear ended about 3 times during the trip.

Enjoy

Scott

 

I had thought the ideal speed was 41, so I sometimes took some back roads and just set the cruise control.

 

I get what I get at whatever the speed limit is. Mysteries come up often.

Like, a new tank of (Chevron) Texaco seemed 'bad' Sunday. 70MPH on I-20 to Augusta should have been maybe 46MPG, but hit 40MPG by the time I got there. So I filled it back up at a BP station and drove home via Route 1. Lots of 55MPH, but 35 and 45 too. Cruise control as often as practical. No heat. When I got home, I was at 54.9MPG over 110 miles.

Why so bad, then so good, all at between 41 and 48 degrees? Beats me, but this is why I can't count on 'secrets', and just hope for the best...

 

I filled up on Wednesday on the way to work so the car was already really warm. The office was only a few miles away and the speed limit was 25 for a brief time and then 35 the rest of the way. The trip from the gas station to the office, I was in EV mode the entire time. That was cool.

 

What he said. Been a "39er" since '01.

 

When I switched to an alternate route that lets me go 35-40 my MPG took a big jump. It was not a huge change, one road over, but the previous route had about 4 miles at 50 mph and long slow hills up and down. But the combination of rolling hills and 35-40 is good. I try for 37-38 for glide so on a couple of hills where I can end up over 41 I can just back off the gas and let MG2 moderate the speed and charge up a bit. Clearly the sweet spot is between 35-40. Can't wait for summer. Warm days, the smell of summer formula gas being pumped and 60+ MPG. The living is easy. Maybe there is a song in there somewhere? :lol:

 

Up to 40 and then glide down to 30-ish, of course, is the pulse-
n-glide technique made famous by the mileage marathoners on their
carefully chosen piece of Pittsburgh secondary highway. ICE on,
ICE off. But all too often we don't have the luxury of driving
for peak mileage, like when that construction guy in the F350
super duty with duallies is freaking behind you at 39.5 mph even
if you're already above the 35 mph speed limit of that stretch.
.
The answer? Pulse up to somewhere > 42 mph, and invoke "warp
stealth". That's a different form of glide -- with the engine
still spinning, so it's not quite as efficient, but in this state
no fuel is injected, and the valve timing is retarded as far as
possible, so it's clear that the system is designed to do everything
it can for as economical a "glide" as it can give you and still
not bring the ICE to a standstill. It's very hard to hold -- just
the barest touch on the accelerator. The MFD will only show arrows
battery --> motor --> wheels, so there's sort of an indication
available, and if you blow it and push down too far the engine
arrows come back on. But this *is* the right answer for high
mileage in that tricky mid-range of speeds from 42 to, say, 60 mph.
The cruise control is fairly good at finding that little notch, in
fact, which is why people report good runs at those speeds ... but
if you know what's going on in there, you can do better manually.
And for the most part, dust that tailgating pickup in the process.
.
For the "instrumented" among us, you'll show about 10A of battery
discharge current, which is probably about what it takes to keep
the dead weight of the ICE spinning at about 900 rpm and gently
push the car. It's not quite enough to maintain speed, though,
so another pulse [in an efficient, high-load manner] is needed.
.
_H*

 

mikepaul, you sure the other factors remained constant? I know for sure that if there's ANY moisture on the road, then my MPG drops 2-3, and heavy rainfall will drop the MPG yet another 2-3 MPG.

Also I noticed that when I'm alone on the road, it seems more difficult to move the car through the air, so I usually do worse than if I'm gliding along with a bunch of other cars in the traffic stream... probably the same reason drafting off a big-rig gets such good mileage.

Finally, did you count ICE warm up on the way to? My early morning ICE startup usually burns a lot more fuel than my late-day (ie, my late day numbers are much higher than early morning ones).

 

I had occasion recently to travel on some relatively rural roads and then passed through a small town with a 35 mph speed limit and one stoplight. The entire route through the town is about 3 miles. As I approached the town, I coasted, and so was at "99.9" mpg. When I reached the 35 mph zone, I was able to maintain the total-electric mode through the entire town, both coming and going. (Fortunately the light was green both times). How cool!

 

Thanks! This is a nice tip for new Prius owners. I have found an alternate route to and from work where I can glide at 39 for a good distance. I am averaging about 54 mph on this route in the winter. I do have to do some highway driving so my winter average is around 49 but up about 4 mpg thanks to your post.