More RPM's = more MPG!

[Wayne M]

More rev's in a lower gear seems to get better mpg (an extra 5 or so) for my situation. Found that by accident after resetting the mpg after a fillup and went daydreaming down the 4 lane (55 speed limit) in 4th for quite a ways. Down here in JawJa it seems to be about 85% uphill where ever you go and with my regular commute I do a lot of those mpg killer loonng hills. When I looked at the mpg readout, like 85 mpg ! I then noticed I was crusin' in 4th at about 50 - 55. So I made a habit of that for the next week and confirmed that for less than interstate speeds, staying in 4th about 90% of the time, unless its a dead flat road, gets better mpg for my area / drive / car / style. This effect seems to be the same idea when one is on a ten-speed bicycle going up a hill in too high a gear range, it takes more leg muscle effort (extra gas / more throttle / low rpm) to keep the same speed over shifting down and cranking a little faster with much less effort ( less gas / less throttle / more rpm ).

Yeah, I know, I watched and 'obeyed' the upshift light religiously too. As much as practical anyway. Till now. Hey, computers ain't always right.

I don't know where the 'full throttle acceleration gets better milage' idea came from . Perhaps it did have a grain of an idea in there somewhere, but full throttle is just that - - no matter how much 'boost' the electric motor gives, it won't offset the fact that you're dumping gas as fast as it'll drink it. Not to mention the clutch / driveline wear.

I don't drive like granny, but keep up with the traffic flow. And with using 4th as my main gear off the expressway, I'm 5 mpg ahead without roasting my engine with cardboard radiator blocks or all the extra plumbing of the hot air thing. My only 'mods' have been a K&N air filter and a cold air intake / ram air thing that cost about $4. A weirdo in every crowd, right?

Hi Wayne:

___At ~ 30 mph in fifth on a flat road with no wind should show you around 120 - 125 mpg. With a very careful DWL technique, you can maintain that FE until such time as something disturbs your progress. 4th? I never bothered given the ICE would be spinning higher Rev’s (more mechanical losses) and more cylinder injections/fires over a given distance.

___Good Luck

___Wayne R. Gerdes

[Insightful Trekker]

AFAI remember these types of findings appear every spring here at IC. Probably what's happening is the warmer temps and the increase in MPG that will result.

However, depending on many factors it is theoretically possible that under your conditions you are truely seeing better MPG. Its just that you could see even better if you'd shift up to 5th and feather the throttle more carefully.

Only you and your MPG meter will be able to tell for sure.

Sincerely,

[Billy]

Wayne from Georgia may be right, to an extent. Just this weekend I put on close to 700 miles, and experimented with this 4th gear thing. Under certain conditions (climbing shallow hills) shifting from 5th to 4th helped me, because I could drive at a slightly higher speed WITHOUT using assist. That way, after the hill is gone, the system does not have to burn energy recharging the pack. My conclusion: generally 5th gear is more efficient, but in some cases downshifting can keep off the assist, therefore giving better FE.

My route was over the Cascade Mtns (twice) and up to Oak Harbor on Whidbey Island. The temps were 30's 40's and 50's, with a rain storm at one point. I mostly had a small headwind. I used FAS when possible, and ended up with 90.7 mpg for 685 miles. Not too bad; just wait until the hot weather comes!

[idfubar]

I've found much the same in my 65 mi. commute from San Jose, CA to Concord, CA which crosses quite a bit of varried terrain. I definitely think a long, flat stretch of highway with even *slight* downhill sloping is better for 5th gear but 4th gear is definitely economical if there a slight uphill, you're foot isn't super-sensitive, or (most importantly) if there's any kind of traffic congestion.

[psuinsight]

I definitely have to use lower gears on many of my uphill climbs in Central PA. The hills I travel are generally not very long but they sure are steep!
If I try to make it in 5th, or even 4th in some cases, my IMA is working overtime and my battery pack drains to about 75%. Then I have to use all the downhill I can for regen I try to gain momentum for the uphill which means I have to punch it sometimes at the start. Then I milk the rolling resistance factor for all it is worth, feather the gas, and keep an eagle eye on the FCD (which is difficult sometimes with shades on). I still try to get back in high gear ASAP. If I am really, really careful I can get over 70 mpg on these hilly, rural roads.

[Subterfuge3927]

Originally Posted by xcel

Hi Wayne:

___At ~ 30 mph in fifth on a flat road with no wind should show you around 120 - 125 mpg. With a very careful DWL technique, you can maintain that FE until such time as something disturbs your progress. 4th? I never bothered given the ICE would be spinning higher Rev’s (more mechanical losses) and more cylinder injections/fires over a given distance.

___Good Luck

___Wayne R. Gerdes

My experience echoes Xcel's, especially with my new battery pack