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Old 09-23-2014, 10:37 AM   #1 (permalink)
MetroMPG
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Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



These brand new Nissan Micras may look identical, and their official fuel economy ratings also say they're almost twins... but in the real world, they're definitely not!

The car on the left has a 4 speed conventional automatic transmission, and the one on the right has a 5-speed DIY gearbox.

Thanks to Cornwall Nissan, last week I got a chance to put the 2 cars through a head-to-head (simultaneous) MPG comparison on a 20 km (12.4 mi) round trip route.

The car's official 5-cycle EPA style ratings:
  • Manual city/hwy/comb: 27.4/36/30.6 mpg US = 8.6/6.6/7.7 L/100 km
  • Automatic: city/hwy/comb: 26.7/36/30.2 mpg US = 8.8/6.6/7.8 L/100 km
(For those of you south of the 49th who don't get the Micra, the car's drivetrain and platform is the same as the Versa sedan/Note.)

Route:
This was a mostly city drive: a mix of urban (~40%, max. speed ~60 km/h = 36 mph) and ex-urban (~50%, max. speed ~80 km/h = 50 mph) roads, with one brief freeway sprint between interchanges (~10%, max. speed 110 km/h = ~68 mph).

Conditions:
cool 10C / 50 F, but sunny & dry.



Driving style: There was actually precious little eco-driving in this comparison, because my dad joined the fun and he led the parade in the automatic. Let's just say that he's a typical driver of the "binary pedal" school (either on the gas or on the brakes). Speeds were around 5 to 10 km/h (3-6 mph) over the posted limit.

To make it a valid comparison, I followed in the 5-speed car and made sure to accelerate as quickly as my dad did in the automatic, and brake as late as he did. There was no neutral coasting, no pulse & glide or anything like that. And I stayed back far enough so there was no unfair aero advantage (draft) for the 5-speed car.

The only significant eco-driving technique I used was upshifting to the tallest possible gear after accelerating. Often that meant 5th gear at as low as 50 km/h / 30 mph on a level road. If I needed more power, I downshifted.


Results:

Forget the official ratings! Once again we see how the EPA testing handicaps manual transmission cars due to dictated, non-eco shift points during dyno testing.




Translation:
  • 5.1 L/100 km - manual (46 mpg US / 55 mpg Imperial / 19.6 km/L) *
  • 6.5 L/100 km - automatic (36 mpg US / 44 mpg Imperial / 15.4 km/L) *
* Note the Micra's onboard display is a bit optimistic. The display in the Micra SR automatic loaner I drove in July read 4.5% higher than actual fuel economy calculated at the pump.


Moral of the story: if you're comparing a manual vs. automatic vehicle based on the EPA ratings, beware of false automatic hope! Even when the numbers are close, a manual is typically capable of better real world economy, and not even using "hard core" techniques. Just upshift early and upshift often. (The extra techniques are gravy.)


A caveat about this test: the conventional torque converter style 4-speed in the Micra is going to fare worse in a comparison against a manual than a CVT or dual clutch auto/robotized manual would. Newer style automatics are definitely closing the gap. But I'd still get the manual, even if the automatic is rated a little higher. (Such as in the case of the Mitsubishi Mirage, where the CVT is rated quite a bit higher, but owners are getting better mileage with the manual in the real world.)


For full details of the Micra showdown: Head to head: 2015 Micra manual vs. automatic MPG/fuel economy comparison - Micra-Forum.com

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Ecodriving test:
Manual vs. automatic transmission MPG showdown: Nissan Micra 1.6L



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