Mpg differences between 5.3 and LS2 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

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Old 06-11-2017, 10:20 PM
BarnesGN BarnesGN is offline
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2008 Pontiac G8 GT
Graphite Metallic 6.0L LS2 V8 2WD
Join Date: Jan 2017
Location: High Point
Posts: 6
Mpg differences between 5.3 and LS2

I fully realize the 5.3 is better but by how much. Let's say 70% city. Anyone owned both?
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Old 06-11-2017, 10:36 PM
AWD V8's Avatar
AWD V8 AWD V8 is offline
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2003 GMC Envoy SLT
Indigo Blue Metallic 5.3L V8 AWD
Join Date: Dec 2014
Location: Surrey BC
Posts: 628
My 5.3 is about 13 MPG city and I drive with a lead foot.

No experience with the other LS engines.
I was planning on procrastinating today but I think I'll do that tomorrow.
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Old 07-12-2017, 09:22 PM
jacklane21 jacklane21 is offline
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2007 GMC Envoy Denali
Fire Red 5.3L V8 2WD
Join Date: Jul 2015
Location: indianapolis
Posts: 88
I just put a mechanics lien on a 2008 SS with 47K miles (nice!)

The thing gets 16 MPG at 70 MPH.

It gets 21 MPG at 45 MPH

City is 10, highway is 15. Those are the CAFE standards or whatever.

But I was on a smooth, flat road and set cruise, and drove 2 miles in each of those conditions to get the baseline of what it can do at BEST.

Of course, city means NOTHING to me, because sitting in traffic is really 0 MPG. Know what I mean? I think here in Indianapolis, I would get about 12-13 MPG the times that I travel in the city. I avoid rush hours at all costs!
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Old 07-12-2017, 10:14 PM
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branndonw branndonw is offline
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2008 Chevy TrailBlazer SS (3SS)
Summit White 6.0L LS2 V8 2WD
Join Date: Aug 2006
Location: Centerton, AR
Posts: 37
My RWD SS got high 13s to mid 14s city and low to mid 17s highway with the 4L70E. I did a TR6060 swap in it and when I first started driving it after the swap, I was driving it pretty conservatively getting the clutch broke in and making sure evertything with the swap was good, I managed to get a 16.1 city. I haven't taken it on a lengthy trip yet, but i'm guessing with the .57 6th gear on the highway with cruise set, it will probably get around 19 maybe 20 if i'm lucky.

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2008 RWD 3SS with a TR6060 6 Speed Manual Trans Swap and Level 2 Monster Clutch
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