Shift points: EPA testing of manual transmissions (why beating MT ratings is easier)

[MetroMPG]

Hi, David - welcome to the forum.

Originally Posted by David Philips

I'd like to hear more manual shift strategies that work to beat EPA numbers. I have a 2000 Miata 6 speed that pretty easily beats the EPA numbers, at least in city/suburban driving in the 30-45mph range.

As far as shifting strategies, get into the highest gear you can, as soon as you can. Next: coast in neutral rather than engine braking or using the friction brakes depending on how much deceleration you need. Those are the two major differences between how the transmission is used in the EPA tests, and how you can use it.

I can get 33-36MPG in suburban driving doing this and short shifting. EPA is 24 city/29hwy.

Sounds like you've got a decent handle on things in town driving already.

You could of course also investigate pulse & glide (engine on or off on the glide), but that's an advanced technique that is arguably mechanically harder on the car, bothersome to the driver/passenger, potentially dangerous (depending on your skill) or illegal (depending on jurisdiction), and may not be appropriate when driving in traffic. But there's no doubt it would raise fuel economy even more.

A peculiar thing I notice at highway speed is that it gets better mileage around 70MPH than in the 55-65MPH range

Colour me respectfully skeptical on that claim. I suspect other factors were affecting your results than cruising speed. This thread shows repeatedly for all types of cars that the slower you can cruise in top gear, the better. I doubt there's anything special about the Miata that makes it an exception to the rule:

http://ecomodder.com/forum/showthrea...you-15182.html

cheers-
Darin

[PaleMelanesian]

Yep - pulse and glide is the best way to deal with high-revving gears. I'm at 3300 rpm at 70, similar to your 3500. Is it possible to change the rear-end gears on a Miata?

[David Philips]

Darin, on the last point it's the 55-65 mph mileage that has always seemed low to me - not so much that the higher speed numbers seem high. Scan Guage shows more spark advance in the higher ranges, but not much - that's pretty load sensitive, too.

[niky]

Other (non-Miata) Mazda owners have claimed the same. Has something to do with engine programming, I suppose.

[serialk11r]

Originally Posted by PaleMelanesian

Yep - pulse and glide is the best way to deal with high-revving gears. I'm at 3300 rpm at 70, similar to your 3500. Is it possible to change the rear-end gears on a Miata?

Wait you get 60mpg with stock gearing??? :O holy ****. How long are your glides? I feel like I can never glide very much since I lose speed super fast and my gears are even shorter (3800 at 70) resulting in ultra short pulses so I gave up on P&G, I just glide when there's a significant downhill grade. Also my brake booster runs out of vacuum after 1 application of the brake pedal so I usually don't engine off down a hill in any situation.

Maybe it's time to try engine off...I was going to regrind my intake cam to lower idle and low rpm pumping loss but I decided not to after realizing it would cost almost 2000 dollars after installination.

[MetroMPG]

Originally Posted by niky

Other (non-Miata) Mazda owners have claimed the same. Has something to do with engine programming, I suppose.

Interesting. Bears investigating!

David - I know a guy who has a Miata - not sure which year it is, though. Is this something that applies to certain years/engines?

[David Philips]

Serial, I think you need to reread the earlier threads.
I have no experience with other year Miatas though looking on Fuelly at people who report their Miata mileage, I'm doing better than most.

[kennybobby]

3500 rpm at 70 mph => 2750 rpm at 55 mph. Would the load be so much better at 3500 rpm as to overcome the additional aero drag power and still beat the 2750 rpm BSFC?

[niky]

Others who report it are owners with FSDE engines (FWD 2.0... completely different engine series)... who claim 65 is better than 55... though I personally get good economy doing merely 50... so take it with a grain of salt.

[Arragonis]

Re- MX-5 economy at speed - MPG displays become less accurate with increases in speed.