FR-S/BRZ MPG

[devinclfalcons]

Originally Posted by serialk11r

You can't compare them because the tests are pretty different. However if anyone wants to get an idea of how high the fuel economy can practically go, may I point you towards my detailed explanations a page or two ago?

It appears these ratings are with the 4.100 rear diff...which is extremely impressive IMO, as the test cycle is not constant speed. If you use a 3.727 then you should be in the 40s on the highway. Considering that it's scoring considerably lower than the Impreza however, I think it's reasonable to expect something like er, 23/31 EPA. I'm still disappointed about the 6th gear

That's with the manual right? I was really hoping to be in the mid-30's hwy

[serialk11r]

You have to distinguish between "EPA highway test" and say 70mph highway cruising. 70mph highway cruising is easily almost 40mpg with the 4.100 diff. With 3.727, you're looking at over 40.

IMO constant cruise power/efficiency is most important, because if you drive right, you can accelerate with extremely high efficiency, and then stick it into 6th as soon as possible.

But yea, 4.100 diff will sorta kill your mpg. 10% less load at these ultra low load levels could be a lot of efficiency lost (probably like 5%). If the spec sheet is not lying about the diff option I think I would want the 3.727. No one needs to be accelerating really fast below 30mph.

Now this compromise wouldn't be so bad if Toyota bothered to fit a tiny bit longer 6th gear to make the car an mpg monster in 6th.

[devinclfalcons]

Did we know what the final drive ratio in the U.S. manual and autos will be? I know you mentioned the auto having a taller 6th gear...

[serialk11r]

Autos seem to all come with 4.100, which negates part of the advantage of their longer 6th gear. Manual with 3.727 final drive would have shorter gearing than the auto.

EDIT: okay quick calculation shows that 4.100 will get you to almost exactly 60mph in 2nd, while the 3.727 would get you to 66. So it will probably come with the 4.100 stock :/ What the fuck Toyota, why is the 6th gear so short? What's the point? This car isn't hitting 180mph!
IMO they should be putting 0.6 or so 6th gear into the car with the same gears 1-5, 4.100 diff. They market the car as something daily driveable and practical, and then kill the highway mpg unnecessarily.

[serialk11r]

Oh sorry for double post, but Future you calculated wrong. The xB's 16.6km/L rating is better than the 86's 12.4km/L. As you said 16.6km/L is 6L/100km. 12.4km/L is 8.06L/100km. It's actually pretty bad fuel consumption wise. :/

Seeing how the Japanese test reads relatively high numbers I'm inclined to believe that it gives constant cruise fuel consumption figures or is an EPA highway test with less slowing down.

[Spaceywilly]

The LSD final drive ratio is 4.1, so all US BRZ/FRS will be 4.1. Only the open diff 86's (G and RC) have 3.723. It is only a difference of .2 km/L in consumption (1.5%) so I wouldn't sweat it.

http://toyota.jp/86/001_p_001/spec/spec/index.html

Oh sorry for double post, but Future you calculated wrong. The xB's 16.6km/L rating is better than the 86's 12.4km/L. As you said 16.6km/L is 6L/100km. 12.4km/L is 8.06L/100km. It's actually pretty bad fuel consumption wise. :/

Seeing how the Japanese test reads relatively high numbers I'm inclined to believe that it gives constant cruise fuel consumption figures or is an EPA highway test with less slowing down.

It is not constant.

http://www.dieselnet.com/standards/cycles/jp_jc08.php



If you see my post above I compared it to the new Impreza and figured it will get around 26mpg, but after comparing to some other cars it looks like you can't really compare JC08 figures to EPA figures at all.

[serialk11r]

Er, where are you getting .2 from?
The ratios are apart by 10%. As I said before, this can easily be over 5% difference in fuel consumption on the highway.
People are used to cars with excessively short cruising gears, so they don't realize just how much more mpg they can pick up. Like I said any small passenger car can cruise at 45-50mpg with the correct gear ratios, as opposed to 35mpg. This is a massive difference. Now of course they know people are too lazy to downshift so they will make the gears a bit shorter but even so, most cars are cruising at around 60-70% peak efficiency or less.

[Spaceywilly]

Originally Posted by serialk11r

Er, where are you getting .2 from?
The ratios are apart by 10%. As I said before, this can easily be over 5% difference in fuel consumption on the highway.
People are used to cars with excessively short cruising gears, so they don't realize just how much more mpg they can pick up. Like I said any small passenger car can cruise at 45-50mpg with the correct gear ratios, as opposed to 35mpg. This is a massive difference. Now of course they know people are too lazy to downshift so they will make the gears a bit shorter but even so, most cars are cruising at around 60-70% peak efficiency or less.

Read the link. GT with LSD is 12.8 L/km. G w/out LSD is 13L/km, on the JC08 circuit listed above. If you drive 100% highway maybe it will be 5% difference, but if you do that don't buy an 86.

http://toyota.jp/86/001_p_001/spec/spec/index.html

edit. sorry, it is 12.4 vs 13, so 4.8% difference. At 30mpg highway that would be 1.2mpg. Big whoop

[serialk11r]

Okay now that I see the Japanese test cycle, it is no wonder that the 4.1 diff doesn't appear to hurt mpg. At speeds that low the fuel consumption is so low that the bulk of the fuel consumption happens in acceleration.

Oh my bad, I didn't notice you could scroll to the right lol. But ^^^ still holds.

City driving this car should be fantastic due to light weight. Sorry if I come off as whiny or something, but it bothers me a lot that the cruising BSFC appears to be 320-350g/kwh rather than 270-300. A sizeable difference for those with long commutes that adds up to hundreds of dollars a year.

[Spaceywilly]

Originally Posted by serialk11r

Okay now that I see the Japanese test cycle, it is no wonder that the 4.1 diff doesn't appear to hurt mpg. At speeds that low the fuel consumption is so low that the bulk of the fuel consumption happens in acceleration.

Oh my bad, I didn't notice you could scroll to the right lol. But ^^^ still holds.

City driving this car should be fantastic due to light weight. Sorry if I come off as whiny or something, but it bothers me a lot that the cruising BSFC appears to be 320-350g/kwh rather than 270-300. A sizeable difference for those with long commutes that adds up to hundreds of dollars a year.

hah no I am just trying to get the facts straight. It is a pain in the ass reading these Japanese sites. I don't know why they don't give us the US specs already. I wouldn't mind if it got 40mpg highway but I am used to 23 so I'll take the extra torque from the shorter final drive and still probably save quite a bit vs. what I spend now.

[serialk11r]

Heh I guess I shouldn't sweat it either, for people who really want to get that extra 10mpg there's pulse and glide (engine on :P it probably helps that the cam is such that idle fuel consumption should be pretty low).

If the STI version does come with a higher redline however, and they decide to bump up final drive ratios, then we're almost certainly going to be around 350g/kwh cruising which is horrible. I imagine listening to 3500rpm on the highway isn't going to be fun either. Hear this Toyota/Subaru? Do the right thing. Put ~0.6-0.65 6th gear into the car. You know you need it to pass the 39mpg compact vehicle regulations coming up.

[devinclfalcons]

So it appears the MPG figures are now official...

http://www.ft86club.com/forums/showthread.php?t=3859

MT: 22/30/25

AT: 25/34/28

The auto gets 34 highway while the manual gets 30. That may have just made my decision as I drive 90 miles round trip to work...

[csaba]

Originally Posted by serialk11r

As far as ground clearance goes, the FRS looks to have as good ground clearance as any cheapo car...ever notice how out of proportion the bodykits look? They have to fill in too much space!

Also EU test cycle gives about 20% higher numbers than US or something...so combined is likely under 30. But what does 35mpg combined EU mean? It means steady cruise on the highway will be >40mpg hehe. EU test cycle reports lower numbers probably because people in Europe drive slightly more intelligently and waste less fuel or something jk I wouldn't know.

The gas in Europe is higher octane up to 98 burns cleaner and has more energy so the cars takes less gas for the same power.

[serialk11r]

Uh, engines are made to operate on a certain octane rating fuel, using higher octane fuel doesn't make it run any better. It doesn't burn cleaner aside from having less sulfur, and the mass specific heat of combustion of alkane fuels (and most hydrocarbon fuels for that matter) are within a few percent. Alcohol/other oxygenates will lower the amount of energy in the fuel by a small amount, but the cooler charges that they produce, among other things, tend to increase efficiency even without a compression ratio increase.