So what is the Mirage's secret? (As efficient as a lighter, smaller engine Metro)

[nternal1]

My MT Mirage is getting gas mileage comparable to my 94 Geo Metro. The Metro had a smaller engine, was extremely aerodynamic and my guess is that it was significantly lighter. How then is the Mirage able get similar fuel economy? Is it the variable valve timing?

[foama]

Its a combination of things. Every piece of a car is a compromise between differing goals, the entire car a sum of all the compromises.

The Metro did not really have good aerodynamics, maybe 0.34 or so. It was a quite simple car, and quite a bit lighter than the Mirage. My Swift was 230kg lighter. The Mirage's VVT makes a big difference for economy. For fast long distance driving, the Mirage is definitely better than the Metro. It has better aerodynamics and more power. At 140kmh in my Suzuki Swift (Metro) your ears would fall of from the noise. With the Mirage I can cruise around that speed keeping up with left lane traffic, and listen to the radio.

[deleted user]

I think there is some serious work going on.

Cam timing, valve lift, fuel injector settings.
I can advance or retard the cam timing, meaning I can open the intake earlier or later. Earlier for top end power, later for variable compression and atkinsonization.
I can increase or decrease valve lift, which also affects compression, combined with throttle by wire things get even more interesting.
Now I can also control when and how much the injector injects. Think of the center of the inducted air mass as being where all of the fuel is, stratified charge possibly without excess NOX.

regards
mech

[Daox]

Ditto on the Mirage's aerodynamics being quite a bit better. The cda is about 10% lower, so the power it takes to push the car through the air is 10% lower.

The LRR tire technology is better.

The engine is definitely more efficient than the Metro's 1980's design:

• No more throttle body injection,
• now we have VVT,
• also higher compression ratio,
• coil on plug ignition (vs a distributor),
• a smarter alternator.

All these lead to less parasitic losses as well as higher engine efficiency. All these things really add up.

[MetroMPG]

The only advantage the old Metros/Fireflies/Swifts had was lighter weight. (The final generation -- which I still own -- wasn't even that mugh lighter than a base 5-speed Mirage: ~140 lbs.)

All the other design & technology advances in the Mirage outweigh the Metro's weight savings, pardon the bad pun.

Where the Mirage absolutely destroys the Metro is if you compare the automatic transmission versions. The Metro's optional agricultural grade, 3-speed, non-lockup slushbox got absolutely horrible fuel economy for such a light, small engine car (as did most of the small, non-lockup slushbox cars back then).

[ahintofpepperjack]

While the VVT does help MPG, it's biggest improvement is it allows for a much wider torque range. A wide torque power band is a huge improvement, especially for low-power cars.

Older cars without VVT, the torque will peak at a specific RPM and drop off rapidly.

[Don]

Ok, I wasn't going to let this info out but as i see this thread isnt going to rest i am going to release some undisclosed information that I discovered as to the real reason the Mirage gets better fuel numbers than nearly anything else on the road.

I know everyone has looked at the design and the transmission and the weight of the car and the LRR tires. All of that would lead you to believe it is the cause of such great fuel economy. Well, I can say that although it probably helped, maybe, atleast a little bit. But the truth is all of those things that are talked and written about are just Distractions to keep you away from the real cause of the Amazing MPG numbers. No other car company can compete with our little Mirage because Mitsubishi knows how to hide the greatest fuel efficiency secret of all time right there in plain sight, under the worlds nose.

Heck even most of the Dealers and mechanics don't know about this. I thought if i post it on the site then enough people would know about it that it wouldn't be putting my life in jeopardy by being the only one who knows.

The car has helium in the paint. it has great stiff suspention that only feels light because of that helium.

[MetroMPG]

I thought I saw a Mirage-shaped weather balloon the other day.

Mustn't have got the paint mixture quite right on that one.

[deleted user]

While the VVT does help MPG, it's biggest improvement is it allows for a much wider torque range. A wide torque power band is a huge improvement, especially for low-power cars.

Older cars without VVT, the torque will peak at a specific RPM and drop off rapidly.

Especially with the 75mm bore and 90mm stroke. Longer lever.

regards
mech

[nternal1]

the car has helium in the paint. It has great stiff suspention that only feels light because of that helium.

whaaaat!!!!