MPG for the Z28

[OldJedi]

I have a 2003 Harley Davidson F-150 Supercrew with the S/C Lightning engine. The best it gets is 15 mpg. But it is not a daily driver, strictly weekends and when needing to move the family around. The Z28 will not be a daily driver either so MPG is not as big a concern. If the CTS-V is getting 15/20 then the Z28 should e close to that. Is there a gas guzzler tax on the CTS-V coupe & sedan?

[Number 3]

Adding a S/C alone will not improve FE. Spinning a power sterring pump is a huge drain on FE which is why so many cars are going to EPS. What do you think spinning a S/C does? It takes fuel to drive that S/C even when not providing boost. And as the advantage of a SC is to be always providing boost more air always requires more fuel.

[556hp]

There is a gas guzzler tax on both coupe and sedan as will be with the sport wagon out later this year. Under normal driving conditions there isn't any boost applied. The 15.2 is average for a daily driver under normal driving. Obviously it goes down the more you crowd the throttle.

[bi11ymc]

My driving habits yield:

2LT Manual 312HP - 16 city / 26 highway (stock)
2SS Auto 400HP - 15 city / 24 highway (stock)
2SS Auto 650HP - 14 city / 22 highway (highly modified)

[alrox]

Originally Posted by OldJedi

I have a 2003 Harley Davidson F-150 Supercrew with the S/C Lightning engine. The best it gets is 15 mpg. But it is not a daily driver, strictly weekends and when needing to move the family around. The Z28 will not be a daily driver either so MPG is not as big a concern. If the CTS-V is getting 15/20 then the Z28 should e close to that. Is there a gas guzzler tax on the CTS-V coupe & sedan?

The CTS-V offically gets 14/19 with the manual and 12/18 with the automatic, prompting a $1300 gas guzzler tax on the manual and a $2600 tax on the automatic. The Z28 should get the same.

[radz28]

Originally Posted by bi11ymc

My driving habits yield:

2LT Manual 312HP - 16 city / 26 highway (stock)
2SS Auto 400HP - 15 city / 24 highway (stock)
2SS Auto 650HP - 14 city / 22 highway (highly modified)

That's not, too dang bad for the mods; did you get rid of the AFM, too? I'm sure it takes a lot more restraint in order to get that mileage though

Originally Posted by alrox

The CTS-V offically gets 14/19 with the manual and 12/18 with the automatic, prompting a $1300 gas guzzler tax on the manual and a $2600 tax on the automatic. The Z28 should get the same.

Hmm... If it's similar on Z28, I'm thinking that stick is looking a lot better. Shoot - straight off I'm expecting another ~$1000 for a converter if I get an auto', so I'd be able to put that toward some simple bolt-on goodies on the M6

[RAYSRT8]

I just added an Edelbrock E-Force Supercharger and Comp Cam and my MPG's went from 16 to 13, but on the flip side my HP went from 417RWHP to 639RWHP. If you want the horespower there is a permanent cost to doing it.

[bi11ymc]

That's not, too dang bad for the mods; did you get rid of the AFM, too? I'm sure it takes a lot more restraint in order to get that mileage though

New camshaft and L99 to LS3 conversion (no VVT or AFM)

[garfin]

Originally Posted by 556hp

There is a gas guzzler tax on both coupe and sedan as will be with the sport wagon out later this year. Under normal driving conditions there isn't any boost applied. The 15.2 is average for a daily driver under normal driving. Obviously it goes down the more you crowd the throttle.

I also have a 2010 CTS-V with a manual tranny. If I'm not mistaken, the A6 has a higher gas guzzler tax than the 6MN in the U.S... ($2600 vs. $1300 for the manual while the auto is a no-cost option in the U.S). In Canada, we pay a $400 "green tax" on all Vs, but the auto is a $1700 option here.

Originally Posted by OldJedi

Thanks for the info 556. I was very curious what the real world MPG numbers are on the CTS-V for City and Highway. Just out curiosity, the highway mileage you obtained is based on what average cruising speed?

I get approx. the same fuel mileage numbers with my V when converting to the U.S. gal and that's at about 72-73 mph with the A/C on. Again, if speculation is correct and the Z comes in a couple of hundred lbs. less than the V. I'd also suspect mileage wouldn't be any worse.
The other "unknown" would be the gearing, which obviously is still speculation.

FWIW, the auto V has a 3.23 rear end with transmission ratios being:
1st 4.02
2nd 2.36
3rd 1.53
4th 1.15
5th 0.85
6th 0.67

Top speed in the auto is limited to 175 mph because the engineers feel the speed of the output shaft needs to be regulated. (manual Vs are not limited and will hit 191 mph.

The manual V has a 3.73 final drive with a dual disc clutch (an absolute joy to drive!!) and gear ratios as follows:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.80
6th 0.63

You can expect fuel mileage numbers to drop noticeably in the colder weather, along with traction (while the power will noticeably increase!) and of course, with power like that, it's a HUGE challenge just to keep your foot out of it!! LOL!
Hope this helps...

Best regards,

Elie

[bolteon593]

Originally Posted by garfin

I also have a 2010 CTS-V with a manual tranny. If I'm not mistaken, the A6 has a higher gas guzzler tax than the 6MN in the U.S... ($2600 vs. $1300 for the manual while the auto is a no-cost option in the U.S). In Canada, we pay a $400 "green tax" on all Vs, but the auto is a $1700 option here.



I get approx. the same fuel mileage numbers with my V when converting to the U.S. gal and that's at about 72-73 mph with the A/C on. Again, if speculation is correct and the Z comes in a couple of hundred lbs. less than the V. I'd also suspect mileage wouldn't be any worse.
The other "unknown" would be the gearing, which obviously is still speculation.

FWIW, the auto V has a 3.23 rear end with transmission ratios being:
1st 4.02
2nd 2.36
3rd 1.53
4th 1.15
5th 0.85
6th 0.67

Top speed in the auto is limited to 175 mph because the engineers feel the speed of the output shaft needs to be regulated. (manual Vs are not limited and will hit 191 mph.

The manual V has a 3.73 final drive with a dual disc clutch (an absolute joy to drive!!) and gear ratios as follows:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.80
6th 0.63

You can expect fuel mileage numbers to drop noticeably in the colder weather, along with traction (while the power will noticeably increase!) and of course, with power like that, it's a HUGE challenge just to keep your foot out of it!! LOL!
Hope this helps...

Best regards,

Elie

^ truth in the above.

[OldJedi]

Originally Posted by garfin

I also have a 2010 CTS-V with a manual tranny. If I'm not mistaken, the A6 has a higher gas guzzler tax than the 6MN in the U.S... ($2600 vs. $1300 for the manual while the auto is a no-cost option in the U.S). In Canada, we pay a $400 "green tax" on all Vs, but the auto is a $1700 option here.



I get approx. the same fuel mileage numbers with my V when converting to the U.S. gal and that's at about 72-73 mph with the A/C on. Again, if speculation is correct and the Z comes in a couple of hundred lbs. less than the V. I'd also suspect mileage wouldn't be any worse.
The other "unknown" would be the gearing, which obviously is still speculation.

FWIW, the auto V has a 3.23 rear end with transmission ratios being:
1st 4.02
2nd 2.36
3rd 1.53
4th 1.15
5th 0.85
6th 0.67

Top speed in the auto is limited to 175 mph because the engineers feel the speed of the output shaft needs to be regulated. (manual Vs are not limited and will hit 191 mph.

The manual V has a 3.73 final drive with a dual disc clutch (an absolute joy to drive!!) and gear ratios as follows:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.80
6th 0.63

You can expect fuel mileage numbers to drop noticeably in the colder weather, along with traction (while the power will noticeably increase!) and of course, with power like that, it's a HUGE challenge just to keep your foot out of it!! LOL!
Hope this helps...

Best regards,

Elie

Elie, thanks so much for the information, it is very valuable. You helped make up my mind between the auto and the stick. It wil definitely be the M6 for me. Between the lower GG tax and the 3.73 gears plus dual disk clutch, it sounds like the way to go at least for my needs. If the CTS-Vs with 3.73 gears are getting in the 15/20 range for city/hwy, that will be good enough. The GT 500 must have just missed the GG tax limit, maybe sometime in the next year Chevy can get 1 or 2 more mpg from the Z28 and avoid the GG tax also. Being from South Florida though i will not be able to take advantage of the really cold air that you get in Canada. By the time a Canadian blizzard gets down here it has already warmed up to 72 degrees. Thanks again, great information.

[radz28]

Originally Posted by garfin

I also have a 2010 CTS-V with a manual tranny. If I'm not mistaken, the A6 has a higher gas guzzler tax than the 6MN in the U.S... ($2600 vs. $1300 for the manual while the auto is a no-cost option in the U.S). In Canada, we pay a $400 "green tax" on all Vs, but the auto is a $1700 option here.

I get approx. the same fuel mileage numbers with my V when converting to the U.S. gal and that's at about 72-73 mph with the A/C on. Again, if speculation is correct and the Z comes in a couple of hundred lbs. less than the V. I'd also suspect mileage wouldn't be any worse.
The other "unknown" would be the gearing, which obviously is still speculation.

FWIW, the auto V has a 3.23 rear end with transmission ratios being:
1st 4.02
2nd 2.36
3rd 1.53
4th 1.15
5th 0.85
6th 0.67

Top speed in the auto is limited to 175 mph because the engineers feel the speed of the output shaft needs to be regulated. (manual Vs are not limited and will hit 191 mph.

The manual V has a 3.73 final drive with a dual disc clutch (an absolute joy to drive!!) and gear ratios as follows:

1st 2.66
2nd 1.78
3rd 1.30
4th 1.00
5th 0.80
6th 0.63

You can expect fuel mileage numbers to drop noticeably in the colder weather, along with traction (while the power will noticeably increase!) and of course, with power like that, it's a HUGE challenge just to keep your foot out of it!! LOL!
Hope this helps...

Best regards,

Elie

Out of curiosity - what RPMs are you turning at around 70 MPH? What - ~2000? I don't recall the height of your tires, but with a 26-inch tall tire, similar ratios in a F-body T56 were around 1900 or something, wasn't it? it's been a while since my LT1, but I think I remember about 1750 with 3.42s on 26" tires

Originally Posted by OldJedi

Elie, thanks so much for the information, it is very valuable. You helped make up my mind between the auto and the stick. It wil definitely be the M6 for me. Between the lower GG tax and the 3.73 gears plus dual disk clutch, it sounds like the way to go at least for my needs. If the CTS-Vs with 3.73 gears are getting in the 15/20 range for city/hwy, that will be good enough. The GT 500 must have just missed the GG tax limit, maybe sometime in the next year Chevy can get 1 or 2 more mpg from the Z28 and avoid the GG tax also. Being from South Florida though i will not be able to take advantage of the really cold air that you get in Canada. By the time a Canadian blizzard gets down here it has already warmed up to 72 degrees. Thanks again, great information.

I'm hoping we get an ESP; I didn't see one on that LSA spy shot, and I believe I saw one on an LSA crate engine. That's save a little gas, and I think that's one of the GT500 features that allow it relatively good mileage. I believe GM will do what it can to keep mileage respectable, relative to the performance. I'm sure there's nothing a little intake and catback mods' won't help improve slightly anyways I guess it won't matter once I swap pulleys

[Jeffro19]

Originally Posted by motorhead

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

Same here!

[bolteon593]

Originally Posted by radz28

I'm hoping we get an ESP; I didn't see one on that LSA spy shot, and I believe I saw one on an LSA crate engine. That's save a little gas, and I think that's one of the GT500 features that allow it relatively good mileage. I believe GM will do what it can to keep mileage respectable, relative to the performance. I'm sure there's nothing a little intake and catback mods' won't help improve slightly anyways I guess it won't matter once I swap pulleys

the esp on my gt500 is loads better then the hydraulic system on the 5th gen currently.


has a much better on center feel, as well as greater responsiveness.


hopefully the z gets a similar system.