MPG for the Z28

[garfin]

Originally Posted by Nine Ball

Where did you find this information? Side by side, I'd say my CTS-V appears more sleek on the nose than a Camaro does. Physcially, the Camaro looks larger than my V does up front, too. I'd like to know the Cd values of both cars.

Cd for CTS-V is .36, according to the Nov. '08 Car & Driver or .355 according to Tuningnews.com (last line in the article)
http://www.tuningnews.net/article/08...ac-cts-v-2009/
Dragoneye has the numbers for Camaro:
http://www.camaro5.com/forums/showpo...79&postcount=1
Camaro SS = .35
Camaro V6 = .36

Best regards,

Elie

[Mr. Wyndham]

Originally Posted by chain777

What do you think the difference in weight will be between the Z/28 and the CTS-V? I'm guessing a couple hundred pounds. The Z/28 should have a slight aero advantage. So I imagine it should be within a mile or two per gallon of the CTS-V. If they manage to avoid a GG tax, it will be impressive.

No more than 200lbs as I see it. Take a second and think about what "will" be on the car.

-Heavier front calipers (6-piston Brembo)
-Lighter front rotors (2-pc Aluminum)
-lighter hood
-lighter wheels (see Z28 spyshots for style/brand of wheel they're testing with)
-heavier tires (285/35 20 vs 245/45 20)
-heavier engine assembly (LSA vs LS3)

I don't think I'm missing anything major....I'll look into the specific weights of the components mentioned above and provide an "accurate guess" a little later, maybe.

Originally Posted by OldJedi

There might be a chance to avoid a GG tax with the manual but not much of chance with the automatic. Just my opinion.

I would definitely agree. Without AFM like the SSs, an auto tranny usually returns lower fuel economy ratings just due to the nature of its design.

Originally Posted by alrox

I think there is virtually no chance of having an LSA powered Camaro getting atleast 15/23 when the CTS-V coupe gets 14/19.

I dunno about that. There's lots of things that we laymen can see that can be utilized to improve efficiency...there's probably a butt-ton more then engineers know of. Ford seemed to find a way to bring a 14/20mpg, 500hp car up to being a 15/23/mpg, 540hp car. And avoid the Gas guzzler tax altogether. I have faith Chevy can do the same...or at least darn close.

Originally Posted by radz28

I do hope they can offset some of that, and believe they'll at least take that into account - I just worry there might be too much to keep at a fair (i.e. GT500) pricepoint. I hope I'm wrong in that respect though.

MM...maybe. I'm certain they're going to be smart about this. But since my ability to get one hinges on a couple grand....I'm with you...REALLY hope they can pull it off.

Originally Posted by Nine Ball

Where did you find this information? Side by side, I'd say my CTS-V appears more sleek on the nose than a Camaro does. Physcially, the Camaro looks larger than my V does up front, too. I'd like to know the Cd values of both cars.

Originally Posted by garfin

Cd for CTS-V is .36, according to the Nov. '08 Car & Driver or .355 according to Tuningnews.com (last line in the article)
http://www.tuningnews.net/article/08...ac-cts-v-2009/
Dragoneye has the numbers for Camaro:
http://www.camaro5.com/forums/showpo...79&postcount=1
Camaro SS = .35
Camaro V6 = .36

Best regards,

Elie

Thanks, Elie -- I was going to quote those same sources!

Drag at the rear of the car, as well as the frontal displacement has a big impact on aerodynamics. Look at the Volt and Corvette, for instance. Intuition tells you that the Corvette would be more aerodynamic...but in fact, the Volt it!

[OldJedi]

Just out of curiosity, what are the magic numbers that the Z28 needs to be able to avoid the GG tax? And do we get any extra credit for being the better looking sport coupe?

[Mr. Wyndham]

Originally Posted by OldJedi

Just out of curiosity, what are the magic numbers that the Z28 needs to be able to avoid the GG tax? And do we get any extra credit for being the better looking sport coupe?

15/23 seems to be the magic number. When the GT500 went from 22 hwy to 23mpg hwy for 2011, it avoided the tax.

Here's the table that tells you if you get hit or not,
http://www.fueleconomy.gov/feg/info.shtml#guzzler

And here's their explanation of the backroom calculations:
http://www.epa.gov/fueleconomy/guzzl....htm#calculate

The Gas Guzzler Tax for each vehicle is based on its combined city and highway fuel economy value. Manufacturers must follow U.S. Environmental Protection Agency (EPA) procedures to calculate the tax. The calculation uses a formula that weights fuel economy test results for city and highway driving cycles (the combined value is based on 55% city driving and 45% highway driving). Fuel economy values are calculated before sales begin for the model year. The total amount of the tax is determined later and is based on the total number of gas guzzler vehicles that were sold that year. It is assessed after production has ended for the model year and is paid by the vehicle manufacturer or importer.

EPA and manufacturers use the same test to measure vehicle fuel economy for the Gas Guzzler Tax and for new car fuel economy labels. However, the calculation procedures for tax and label purposes differ, resulting in different fuel economy values. This is because an adjustment factor is applied to the fuel economy test results for purposes of the label, but not for the tax. The adjustment is intended to help account for the differences between “real-world” and laboratory testing conditions.

EPA conducts fuel economy tests in a laboratory on a dynamometer (a device similar to a treadmill). Laboratory conditions can be different from real world conditions for such parameters as vehicle speeds, acceleration rates, driving patterns, ambient temperatures, fuel type, tire pressure, wind resistance, etc. EPA studies indicate that vehicles driven by typical drivers under typical road conditions get approximately 90 percent of the laboratory test-based city miles per gallon (mpg) value and approximately78 percent of laboratory highway mpg value. This difference is referred to as “in-use shortfall.” To account for the in-use shortfall, the city and highway mpg values listed in Fuel Economy Guide and shown on fuel economy labels are multiplied by 0.90 for the city test and 0.78 for the highway test. However, the combined city and highway fuel economy that is used to determine tax liability is not adjusted to account for in-use shortfall, so it is higher than the mpg values provided in the Fuel Economy Guide (www.fueleconomy.gov) and posted on the window stickers of new vehicles."]The Gas Guzzler Tax for each vehicle is based on its combined city and highway fuel economy value. Manufacturers must follow U.S. Environmental Protection Agency (EPA) procedures to calculate the tax. The calculation uses a formula that weights fuel economy test results for city and highway driving cycles (the combined value is based on 55% city driving and 45% highway driving). Fuel economy values are calculated before sales begin for the model year. The total amount of the tax is determined later and is based on the total number of gas guzzler vehicles that were sold that year. It is assessed after production has ended for the model year and is paid by the vehicle manufacturer or importer. EPA and manufacturers use the same test to measure vehicle fuel economy for the Gas Guzzler Tax and for new car fuel economy labels. However, the calculation procedures for tax and label purposes differ, resulting in different fuel economy values. This is because an adjustment factor is applied to the fuel economy test results for purposes of the label, but not for the tax. The adjustment is intended to help account for the differences between “real-world” and laboratory testing conditions. EPA conducts fuel economy tests in a laboratory on a dynamometer (a device similar to a treadmill). Laboratory conditions can be different from real world conditions for such parameters as vehicle speeds, acceleration rates, driving patterns, ambient temperatures, fuel type, tire pressure, wind resistance, etc. EPA studies indicate that vehicles driven by typical drivers under typical road conditions get approximately 90 percent of the laboratory test-based city miles per gallon (mpg) value and approximately78 percent of laboratory highway mpg value. This difference is referred to as “in-use shortfall.” To account for the in-use shortfall, the city and highway mpg values listed in Fuel Economy Guide and shown on fuel economy labels are multiplied by 0.90 for the city test and 0.78 for the highway test. However, the combined city and highway fuel economy that is used to determine tax liability is not adjusted to account for in-use shortfall, so it is higher than the mpg values provided in the Fuel Economy Guide (www.fueleconomy.gov) and posted on the window stickers of new vehicles.

So,
15 city / .9 = 16.7 city used for GG
23 hwy / .78 = 29.5 hwy used for GG

(16.7 x .55) + (29.5 x .45) = 22.5

I rounded up in places....I think their exact multipliers are a tad different.

[OldJedi]

Dragoneye, thanks for being able to decipher the above. And a special thanks for doing the math. It never really was my strong point in school. So we need 23 mpg or have to pay up to play. I still think we should get extra credit points for having the better looking car.

[thePill]

As it currently stands, the GG tax starts at 22.5mpg at $1000 and increases up to $7500 under 12mpg. I cannot see the 6A or 6M avoiding the 22.5mpg standard.

Adding up the shipping weights of the intended Z28 upgrades put the LSA/TR6060 (with M12/MG9 gearset and Dual clutch) at 4042lbs and the LSA/6L90 at 4076lbs alone.

Factoring in the 15/14.7" (which are a 1/2" thicker, 1" wider in front and 1/4" in back) CTS-V disc and 6 piston cals add 8lbs up front per wheel and 5lbs rear DRY= 26lbs. Regardless of the dual bonded aluminium caps, the extra disc size will add some weight.

Add the additional weight from the larger AL wheel over the stock SS ALs without rubber (3lbs, 5lbs with rubber) brings the Z28s weight to 4088lbs manual, 4122lbs auto based on availible shipping weights. You got to watch the word "lightweight" when talking parts, lightweight? sure, lighter than the stock unit it replaced even though it increased in size and made from the same material? unlikely.... Suspension will also see a weight increase but how much is unclear.

Also, the Camaro is physically a bigger car than the CTS-V as far as wheel base/track width. Unless GM shaves weight elsewhere, this will be a heavy car.

FYI: The 2010 Camaro did not receive a 5 star crash test rating overall. It received a 4 star rating in both driver and passenger front collision. GM cannot take any meat from the frame that it hasn't done already. Could be the main reason the Vert was delayed so long, All Verts receive a zero rating for rollovers and out of a score average of 4,4,5 and 0 would make insurance unbearable.

As long as the LSA manages MPGs like the CTS-V it won't be so bad... just expensive vs. the GT500.

[SuperH]

Originally Posted by alrox

Z28 will have a gas guzzler tax.

Nah it won't. They'll have AFM to shut off 6 out of 8 cylinders on the automatic version, and 1-6 shift on the standard transmission version!

[Mark H]

This is some great info guys.
Keep
Up the good work.

[thePill]

Depending on the version of the TR6060 (M12 or MG9) GM goes with will dictate the final gear ratio. The MG9 set found in the current CTS-V uses a high 2.66 first gear ratio accompanied with the 3.73s in the rear. The lower M12 used in the Aussie cars have a 3.01 (close to the current 3.01 TR6060 M10 LS3 mated trans) and could still use a 3.45-3.73. Although the M12s are a distant possibility, HP rating and durability might be an issue if the M12 comes to the table... but stock performance, cost and possibly fuel efficiency could over shadow the MG9s.

Both the M12 and MG9 could add alittle weight over the stock TR6060 M10 used now but don't expect anything over 10lbs, even for the beefy MG9.

As far as the auto goes, the 6L90 is a lock because it is superior to any stock auto GM offers now. It is aliitle heavier over the 6L80 (209lbs vs 240lbs both wet), but they can handle horsepower and distribute torque to the rear wheels without blowing the tires off.

I forgot my point.... oh, MPG... the 6L90 may have a chance to meet the standard as long as the final gear ratio is at the stock 3.45. The TR6060 could meet the standard if the old M12 and MG9 is used with a 3.45 as well... smaller wheels would help too, maybe a thick 19".

edit: if the 6060 uses a dual clutch, expect the 10lb gain to increase to almost 30 in both M12 (if available) and MG9...

Sorry for the edits, I am stuck with an iPhone at Hotel Burgschaenke in Hohenecken, Gemany.

[Mr. Wyndham]

.

Originally Posted by thePill

Adding up the shipping weights of the intended Z28 upgrades put the LSA/TR6060 (with M12/MG9 gearset and Dual clutch) at 4042lbs and the LSA/6L90 at 4076lbs alone.
If the Camaro team engineers were aftermarket consumers...this logic might work. But they have the distinct advantage of being able to make things to how they want it. It's an incredible variable to factor in...rendering all of this to guesswork.

Add the additional weight from the larger AL wheel over the stock SS ALs without rubber (3lbs, 5lbs with rubber) brings the Z28s weight to 4088lbs manual, 4122lbs auto based on availible shipping weights. You got to watch the word "lightweight" when talking parts, lightweight? sure, lighter than the stock unit it replaced even though it increased in size and made from the same material? unlikely.... Suspension will also see a weight increase but how much is unclear.
The tires should be about 2lbs lighter per corner than stock, and the wheel's wieght will hinge largely on the spoke design and material thicknesses, as well as width. It could be that they're heavier, the same, or even lighter than the SS's.

And you understand exactly what I mean when I say "lightweight". No reason for me to watch it, then.

Also, the Camaro is physically a bigger car than the CTS-V as far as wheel base/track width. Unless GM shaves weight elsewhere, this will be a heavy car.
Actually, it's not. Camaro's wheelbase is shorter by about an inch and a half, it's shorter, and shorter than the CTS-V. The Zeta architecture, just by its nature, is also somewhat lighter than the Sigma chassis.

FYI: The 2010 Camaro did not receive a 5 star crash test rating overall. It received a 4 star rating in both driver and passenger front collision. GM cannot take any meat from the frame that it hasn't done already. Could be the main reason the Vert was delayed so long, All Verts receive a zero rating for rollovers and out of a score average of 4,4,5 and 0 would make insurance unbearable.
Thank you for that. I'm aware what the crash test ratings are...notice I didn't say 'overall'. Not to mention the fact that those tests don't necessarily tell the whole story...like EPA fuel economy tests, they are not dynamic at all.

Nice theory on the vert, but the reason it was delayed was the roof supplier. The original German company went out of business some time ago, and they needed to attend to that. They've done their homework on the safety of the convertible, so I hear.

As long as the LSA manages MPGs like the CTS-V it won't be so bad... just expensive vs. the GT500.All research indicates the Z28 should be able to achieve higher fuel economy ratings than the CTS-V. As well, it shouldn't be any more expensive than the GT500. IF they simply copy the CTS-V...shady math...but it's the best we've got since we're not on the team.

[thePill]

Ah yes, the wheelbase is 113.4 vs 112.3 but overall length this year is 188.5 (previously 191) vs the Camaros 190.4, Track width is 61.8 fr/62.8 rr vs the 63.7 fr and rear of the Camaro. Overall width is 74.1 vs 75.5 but the Camaro has a 54.2 roofline (55.9 for the CTS-V. So where the Camaro gives an inch in the wheelbase, it takes it back in almost every other dimension.

Looking at the weight of the LSA, wet and ready to run will add 132lbs to the LS3s 418lb. Even extreme weight saving measures taken in the LS9 only saved 20lbs (529.9lbs). I'm not sure engineers want to open up an LSA to lightnen it. Both 6060 and 6L90 look to gain 30lbs depending on the dual clutch option/gearset in the 6M. The 6L90 is 31lbs heavier than 6L80 at 240lbs.

It wouldn't surprise me to see a 200lbs weight increase. Every auto that under goes FI gains 200lbs on average.

[Whorable MPG1975]

I don't think anybody looking to buy a Z/28 will care a whole a lot about MPG. I know I won't.

Amen! Still, forgot about the gas guzzler tax. If the auto trans is a no cost option I can take that pill though. I hope it comes with 3.73's though!!

[Mr. Wyndham]

Originally Posted by thePill

Ah yes, the wheelbase is 113.4 vs 112.3 but overall length this year is 188.5 (previously 191) vs the Camaros 190.4, Track width is 61.8 fr/62.8 rr vs the 63.7 fr and rear of the Camaro. Overall width is 74.1 vs 75.5 but the Camaro has a 54.2 roofline (55.9 for the CTS-V. So where the Camaro gives an inch in the wheelbase, it takes it back in almost every other dimension.

I really don't want to split hairs here, but the CTS sedan stayed as long as it has been. The coupe has the shorter length, and that can be attributed to revised fascias...not significant framing adjustments, where any measurable weight would be.

[thePill]

Originally Posted by Dragoneye

I really don't want to split hairs here, but the CTS sedan stayed as long as it has been. The coupe has the shorter length, and that can be attributed to revised fascias...not significant framing adjustments, where any measurable weight would be.

I agree, that's why I stated that the Camaro is "physically bigger" and not heavier. Weight savings would have to come from exhaust, suspension (probably not), exterior panels and interior. Interior will be quality and comparable to the competition, so weight loss is probably a no go there.