Auto vs manual (why are some automatics' MPG ratings higher on the highway?)
 

I'm new here and hope I don't ask questions that have been covered. Here goes.

I'm driving an 03 Celica now and it's a decent car economy-wise. But I'm considering trading for a Civic or a Saturn SL/SC or something like that.

Anyway, while perusing the EPA estimates on fueleconomy.gov, I noticed that now and then a small car such as the aforementioned will have a better mileage rating for the automatic trans version than for the manual.

I'm having a real real hard time understanding/believing that. Clue me in :)

i've always seen the opposite for many models i've compared.
welcome aboard!

Many of the manual versions that are rated lower than the auto version are the "sport" packages, so they're geared a bit lower. In real world usage, it is easier to exceed the EPA estimates with a manual because the driver can choose exactly when they want to shift and not have to coax the transmission into shifting.

techanic -

I agree with vskid3's explanation. I wanted to say that it's the "luck of the EPA test", but it makes sense that the manual trannys would be sport-tuned.

CarloSW2

There are more hypermiling techniques available to the MT driver around town, especially if the car doesn't have throttle by wire. If you get the stick shift, expect to beat EPA City by a larger margin than with the auto.

However, on the highway, you want whichever tranny has lower RPM's at your cruising speed. For Hondas, that's the 5-speed automatic or the CVT.

When it comes time to turn in the Tempo, my next car will definitely have a manual tranny. I'm tired of automatic. XD

This 3 speed NEEDS a 4th gear. Buzzing at 3K RPMs at 60 MPH is too high.

Exactly what I was going to say.
My old Altima auto at 75mph (before I got into hypermiling :D) would do about 3000ish RPM. I later converted that car to a manual transmission, everything else the same, and the gearing and final drive was higher at 75mph, and I cruised now at about 3500rpm and got slightly lower MPG.

But the take home point is that unless almost all of your driving is on the highway (or unless there's an enormous difference between the auto vs. manual ratios), you'll still likely never beat the overall (combined) fuel economy of a manual.

There are many automatics today that will beat a manual transmission in over all real world fuel economy. Because the newest automatics are computer control and can switch gears seamlessly, they can afford to always utilize a very tall gear for constant load while downshifting as soon as you want to accelerated. Basically they shift gears a lot more often than a driver ever would. 6 speed automatics are becoming the norm even in cheap cars while more expensive cars have 8 speeds. VW and a few others (ford fiesta) are using dual clutch automatic transmissions that don't have a torque converter anymore. They also shift into neutral when sitting at a light with your foot on the brake. I think automatics to quickly drop in price to the point that the manual transmission disappears completely. Internally the newest automatic transmissions looks a lot more like manual transmissions with synchrony and shift forks instead of clutch packs and valve bodies.
http://www.youtube.com/watch?v=3JtTTyalbd4


EDIT: have you noticed how just about everyone except nissan gave up on the CVT?

Gearing. For steady-state cruising it's possible to have a tiny final gear that makes good mileage possible when it's not shifting constantly.