City ecodriving comparison: 2014 Mirage CVT vs. Mirage 5-speed vs. 1998 Metro 5-speed

[MetroMPG]

Originally Posted by 2007 ion2

I think they're still handicapped by needing a pump, manifold, torque converter, and more rotating mass than a manual transmission, and more parasitic loss from the hydraulic systems

True enough. It was funny -- while testing the Mirages, the salesman who rode with me was describing the CVT as superior to the manual: "it will always go to the best RPM for torque or efficiency, depending on the driver's demands. It will even hold the ideal RPM for max power while accelerating at full throttle."

I asked: "So why does it accelerate slower than the manual?"

He didn't have an answer.

[gone-ot]

Originally Posted by MetroMPG

I asked: "So why does it accelerate slower than the manual?"

He didn't have an answer.

Optimum acceleration occurs at maximum HP, not at maximum torque nor minimum BSFC, which the CVT is tuned to operate at.

And, since HP is a combined function of how often torque is being produced, it (HP) is simultaneously a rising function of RPM and a falling function of torque (which "peaks" between 2/3-3/4 of engine max HP RPM), ie: HP increases so long as torque is increasing, but decreases as soon as torque begins to stop increasing:

HP = (T*RPM)/5,252

[niky]

True enough.

The Mirage CVT, however, has a "Brake" function, which allows it to hold revs at the horsepower peak from what is technically the end of "first gear" (where the CVT's lowest ratio allows it to hit 5,500 rpm... the hp where the dyno says the stock motor hits its hp peak).

In our testing of the Mirage over the past two years, we've been lucky to have both the manual and CVT variants available on the same testing days, for both basic and loaded "GLS" trims, for the hatch and sedan.

Discounting the "launch" advantage of the manual by subtracting the 0-60 km/h time from the 0-100 km/h, you still get a slight advantage 0.2 second advantage in acceleration times between 60-100. But that's not the whole story. Having to shift the manual from second to third to hit 100 km/h (62 mph) typically wastes about 0.2 seconds of time due to the interruption of torque. In the Mirage it's worse, because the upshift puts you just below the MIVEC changeover point, and there's an added delay before acceleration resumes. Some cars have turbo-lag. The Mitsubishi has valve-lag.

The increment between 60 and 80 km/h, which you can do in just second gear, effectively simulates "in-gear" passing. Here, the manual is nearly a second faster. The CVT definitely has a big effect on power there.

Of course, this means little on the road, since most people take about half-a-second to a second to complete a shift. And with a full load, you'll appreciate the ability to sidestep that lag in acceleration with the CVT.

[AJI]

Hi Darin, finally got around to reading this thread (I don't post on EM nearly as often as I should).

Really great results you got from both Mirages there. I've still only driven the manual but did get another go in the car back in August, so managed to come up with a few figures of my own.

Now unfortunately, the Mirage's MPG display resets every time you turn off the ignition, so I've no idea what I averaged over a week. The figures were still good though. I have a freeway route nearby I use for steady-speed economy tests - it's a 50-mile route (25 each way to minimize the influence of wind direction) at a steady 70 mph, the UK speed limit. It also includes any deceleration/acceleration at the end of the first 25 miles where I exit the freeway, drive under it and re-enter it.

On that, I managed 54 mpg IMP, which is 45 US - 3 mpg above the EPA highway rating for the manual

Generally, I found figures in the 50s (IMP) fairly easy to achieve. It only dipped into the 40s (IMP again) when I started driving a bit harder - it does seem to be one of those cars capable of reasonable gas mileage however you drive it.

Unfortunately, as the review shows, I'm still not much of a fan of the car itself. I really want to like it (it's just a good, honest, frugal small car with a spacious interior) but over here in the UK we just have too many other small cars that do the same job better for the same (or less) money. Still, apparently sales of them are doing okay over here.

Edit: A pic, why not?...

[MetroMPG]

Thanks for the update, Antony.

FYI, there's a second fuel consumption gauge in the MID (or a setting... I forget which) that let's you display a long term result vs. auto-resetting short trips.

Mitsu's EPA ratings for this car are conservative.

24 owners posting at MirageForum are beating the EPA on average (collectively around 41 mpg US, with a high of 59 and two stinkers at 29). Interestingly, the manual drivers are doing better than the CVT owners, despite the CVT'S better rating. A slightly older analysis... MirageForum Fuel Log stats: 19 Mirages, averaging 42 MPG, 17.9 km/L, 5.6 L/100 km

Could be for a variety of reasons, but one of them is because the manual is simply rated more conservatively than the auto.

[ssnsvibe09]

Anybody aware of the mirage going into coast mode automatically and dropping the RPM, in light downhill grades?

Once I got my engine interface I discovered that my engine would go into DFCO very easily. Urban driving in 5th is real efficient compared to being forced to cruise in traffic at 100KPH on the highway.

[AJI]

Originally Posted by MetroMPG

Thanks for the update, Antony.

FYI, there's a second fuel consumption gauge in the MID (or a setting... I forget which) that let's you display a long term result vs. auto-resetting short trips.

Ah, that's interesting to know. I did cycle through and couldn't find it, so either I wasn't looking very hard or Euro-market versions don't have such a setting. Who knows.

And yeah, it does look very much like the EPA ratings don't show it at its best, which isn't bad considering the Mirage is already among the highest-MPG non-hybrids. It's a pity European figures are so optimistic. I dug into the two tests a while back; there's only about a third the drive time on NEDC there is with the EPA, or something ridiculous like that. And average speeds are quite a bit lower.

Unless you drive everywhere at 45 mph (or have a car absolutely not optimized for the tests), European economy figures are pretty hard to hit. Fairly recent phenomenon too - I quite comfortably beat the Euro figures in the old Ford Fiesta I had when I first joined EM.

I may see if Mitsubishi UK has a 1.2 with the CVT or even the smaller 1.0 version at some point - would be interesting to compare with the 1.2 manual I've only driven so far.

[MetroMPG]

If you were only "so so" on the manual car, I predict you'll not like the CVT. There seems to be a clear divide on reviews of the 5MT vs. the CVT in North America, at least.

I wish, wish, wish the 1.0L were available here. We've got a poll running on MirageForum, and more respondents (even here on the power-hungry continent) are saying they would have chosen the 1.0 over the 1.2, even without trying it first. The difference is about 7% better fuel economy, ~9% less horsepower. Self-selecting sample, of cours.e

EDIT PS: the non-auto-resetting MPG gauge option is in the Asian cars as well as the North American ones. I'm pretty sure it's a feature in the Euro/UK cars too.

[3 Banger]

Originally Posted by MetroMPG

A couple of downshifts into "B" mode for sustained deceleration fuel cut-off. (PS: downshifting a CVT is kind of fun -- completely unlike other automatics or manuals!)

"B" mode actually raises the RPM in the Mirage keeping it at about 4000. They call it "B"rake mode because it its like down shifting in a manual to help slow down. We pretty much all know down shifting to slow down kills your mpg (and it's a lot cheaper to replace break pads than it is an engine, tranny, or clutch). "B" mode is like shifting into a lower gear in an automatic (like D to 3 or 2) to help climb on steep hills or "B"eef up the output. Pretty much you hurt the mpg test here by shifting into "B". If you could, do the test again without "B" mode and see what you get. Thanks!

[MetroMPG]

B mode actually can help fuel economy in certain circumstances: namely when you have to slow down more than coasting would accomplish (e.g. if a light changes in front of you). B mode can engage deceleration fuel cut-off (zero fuel use) sooner and longer than drive mode.

Won't argue with you on the question of additional wear, though I'd bet it's negligible.