100+ hypermiling / ecodriving tips & tactics

[Frank Lee]

Yes, the T-Racer is an automatic and it goes into OD lockup at 37 mph which can be held down to about 35 mph if careful. I presume it delivers better fe in OD so I want to cruise at at least 35 mph even in 30 zones. That is pretty much the only situation I ever speed but I hesitate to recommend it because of the exposure to ticketing.

[MetroMPG]

Originally Posted by UnicycleDan

Another example to see if I understand: speed limit 35mph. If my car shifts gears between 35 and 40, it's better to drive at 40 in the higher gear, lower rpm. If there is no gear shift between 35 and 40, drive at 35mph.

You've got it. The tip is more for highway cruising.

On that point: why is your car most efficient at 55 mph - is that where it shifts into top gear? (Seems high to me.)

If you look at our big collection of speed vs. fuel economy charts, there aren't any that get better mileage as speed increases beyond that final shift.

[PaleMelanesian]

Originally Posted by MetroMPG

You've got it. The tip is more for highway cruising.

On that point: why is your car most efficient at 55 mph - is that where it shifts into top gear? (Seems high to me.)

If you look at our big collection of speed vs. fuel economy charts, there aren't any that get better mileage as speed increases beyond that final shift.

That's true in ideal conditions, but in real world with terrain variation it's often better to be a bit faster. In my Odyssey I find 55 is a good compromise. 45 is ideal, but the first hill you find it'll downshift into fuel-sucking 4th gear. Starting at 55 you can let the speed creep down to 45 and still be in top gear.

[MetroMPG]

True. There are always asterisks. 55 is a good compromise if you face hills that would require constant downshifts.

Where I drive, there aren't many of consequence, so I could slow down a bit and keep it in top gear.

[PaleMelanesian]

Originally Posted by MetroMPG

True. There are always asterisks. 55 is a good compromise if you face hills that would require constant downshifts.

Where I drive, there aren't many of consequence, so I could slow down a bit and keep it in top gear.

Wait, you mean... YMMV?

[MetroMPG]

Something like that! What a concept.

[UnicycleDan]

To quote MetroMPG, "On that point: why is your car most efficient at 55 mph - is that where it shifts into top gear? (Seems high to me.)

If you look at our big collection of speed vs. fuel economy charts, there aren't any that get better mileage as speed increases beyond that final shift.[/QUOTE]"

Oh, boy...now there seem to be mixed messages. Honestly, I pulled the 55mph number out of what I think I've heard before concerning FE, so almost out of nowhere. In an article on your metrompg.com entitled "Speed kills: testing MPH vs. MPG in top gear", you said "Here's one from the EPA for an unnamed vehicle (in unknown conditions) which shows a mileage peak around 50 mph - likely where the highest gear is engaged." Then you show a graph below. My interpretation of that sentence anyway is that lowest speed in highest gear yields optimal FE. And the VW Golf graph below it indicate the same concept. I have a non-hybrid, so wouldn't that be true for me, too...lowest speed in highest gear gives best FE? Or am I misinterpreting something here? Your last sentence contradicts this, though. I tried to follow the link on the words "collection of speed vs. fuel economy charts" and I didn't find a "big" collection, but rather 2 charts, both of tiny cars, far different from my large automatic SUV. I guess some clarification would be nice. Thanks.

[MetroMPG]

My mistake: I posted the wrong link. It's:

Speed vs. MPG charts (post 'em if you got 'em) - Page 13 - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com

My interpretation of that sentence anyway is that lowest speed in highest gear yields optimal FE. And the VW Golf graph below it indicate the same concept. I have a non-hybrid, so wouldn't that be true for me, too...lowest speed in highest gear gives best FE?

You're not misinterpreting it at all. With the exception of conditions where cruising just above top gear isn't possible because of hills (PaleMelanesian's post, above).

[UnicycleDan]

Thank you, Metro

[RedDevil]

Under most conditions and especially when going against the wind my Insight gets best economy around 58 km/h (35 mph) where the (drum-belt system) CVT maxes out and the revs begin to climb if I go faster.

With the wind that resistance is less of an issue and I can get somewhat faster without suffering FE wise. The CVT stays maxed out at higher speeds unless I accelerate or go really fast. Above 55 mph I rarely get top FE though.

Going slower than 30 mph will see it use EV mode every now and then, which uses DFCO but still spins the engine. Revs will stay at around 1000 RPM. And inevitably it will need to recharge the battery, getting relatively bad FE on that part. The losses due to extra engine rotations and charge/discharge are bigger than the gains from less air resistance, AFAIK. It is hard to maintain good FE numbers when going slow for a long time.

Toyota's HSD 'CVT' gearbox has no upper mile per rev limit so I guess best speed for FE on that varies even more with conditions than on mine.