For efficiency, the goal is to have a motor that CAN make power on throttle, but at cruise can get by making only as much power as needed to maintain speed. An ideal motor would make very little power at a constant vehicle speed.

I'm not really sure what the differences in transmissions are. Any reference help on how the models differ and how it affects driving feel would be appreciated.

 

I test drove both LS2 and LS3.. before choosing the LS2, and here are the reasons I went with the LS2.

1) I saved atleast $5k buying an '07 instead of '08. Prices really skyrocket when looking at both model years. Saving $5k is ALOT for essentially the same vehicle when you really think about it.

2) There was a small seat of the pants difference, but realistically 400hp is already more than hp for anything I'm going to do on a public road. If I was looking to hit the track more, drag race the car, or otherwise go for some large HP number I would have chose the LS3 car.

3) The LS2 is rated 18/28mpg vs 16/26mpg for the LS3. With gas now $4.60 a gallon for premium in the DC area.. every little bit counts. Driving the car home from Kansas City, MO to the Washington, DC area.. I averaged 28.5mpg driving speeds between 75-80mph.

4) The LS2 is available with the Z51 package, which gives quicker acceleration and slight shorter gearing. I'd much rather have a Z51 LS2.. than a non-Z51 LS3 and stay within my budget.

5) If in the next year or so, if I find that I'm really concerned about power. I wont bother modding my LS2 at all. I'll simply trade up to a '08 Z06 or a '10 GS with NPP. My main reason for wanting the LS3.. was the smoother transmission, better steering feel, and black/CF center dash. But I simply didnt think it was worth the $5k upgrade when it was all said and done for a car that essentially looks identical (the '07 vs the '08).

When you start adding in all of the "little things" that coming with the '10 GS.. like widebody kit, bigger brakes/rotors, wider wheels, NPP exhaust, factory integrated BT, performance traction control.. then it starts to become a more attractive upgrade to me and one that seems well worth paying for. Of course it will be much more of $5k difference.. but in a year or so.. there will definitely be some 3 year old '10 GSs or 5 year old Z06's floating around in my price range.

 

The EPA revised the gas mileage estimates that is shown on the car's window sticker to better reflect the way people actually drove their cars. This just happened to go into effect at the same time that the LS2 was replaced by the LS3. If you check the gas mileage of the Z06, you will find the LS7's gas mileage also dropped at the exact same time, even though the LS7 did not gain any additional displacement or horsepower, as did all cars of all manufacturers, accross the board.

 

We took two almost identical road trips of over 4,000 miles in our 2006 and then 2009, both A6. Only difference in the cars was the LS2 vs LS3, and the LS3 also has the performance axle.
LS2 = 25.8 mpg
LS3 = 25.3 mpg

Both trips, lots of high speeds but also crawling in traffic at times.

 

From EPA's website...

"In December 2006, EPA issued updated test methods to determine the fuel economy estimates (city and highway) that appear on the window stickers of all new cars and light trucks sold in the U.S., beginning with 2008 models. For more information about the updated methods, see EPA's Final Rule."


The LS3 is a marvel of an engine. Increased displacement, increased horsepower and increased performance and it still get basically the same gas mileage as it's predecessor. Now if only the 427 ci, 505 HP LS7 could get 30+ MPG on the highway....oh, wait, it does.

 

The LS1 to LS2 was a difference of 50HP. THAT can be felt.

 

Everyone's Butt-O-Meter is calibrated differently.

When we went from our 2001 A4 (350 hp) to the 2006 A6 (400 hp), I could barely notice the difference.

But going from the 2006 (400 hp) to the 2009 (436 hp) was like WOW!

I can't explain that, but that's how it felt to me.

 

,we always got north of 30mpg with the 05 auto,,,and find it hard to get 30mpg with the 08

now very often will we get north of 30mpg with the 08 auto,

,,,the biggest difference between the 05 and 08 was the transmission,,,it is very tame compared to the 05 auto 4 speed,,,at 30-45 mph the 05,if it hooked up was crazy when you floored it,,,,the 08 auto much nicer,,,,

 

LS3:
Better heads
Better intake manifold
Better cam profile on the intake side
More cubes
Slightly less compression
Some block enhancements

Vehicle:
Some interior bits
Enhanced feel for the steering rack
TR 6060 trans I believe, stronger and supposed smoother shifting


LS2:
Slightly more compression

 

I would think that hwy MPG is best calculated by putting the car in cruise at highway speed on a level road and reading the instant MPG. Considering speed limits on highways rarely exceed 80 and are usually closer to 65-70, I think this would be a fair real-world estimate of what you can expect if you're actually cruising.

 

I averaged 29.4 according to my car's calculation.

08 with Headers, Xpipe, Intake.

Gas Mileage shouldnt be an issue

 

When the EPA first started with their estimates the speed limit was 55 MPH(1974-1987) and that was the speed that was used in their highway estimates. When they revised their estimates, it was based party on people driving at higher speeds then 55 MPH.

 

I'm an LS2 owner. The engine is very reliable and maintenance free. I personally can't justify the expense of acquiring another C6 just for the LS3 engine upgrade. I am waiting for the C7. I will just limp along with only 400 hp for the time being.

 

Good attitude!
Any C6 is a great car.

Two friends in our club have 2005 A4 Corvettes, and they have just as much fun as the rest of us.

 

2010 COUPE LS3 CAI,PORTED TB,PORTED INTAKE,B&B EXHAUSTand a SPRINT BOOSTER!.... pulls harder than my 2006 LS2 same mods... heres a good word the LS3 seems more "refined"

 

This is why I just pulled the trigger on the LS3.

For some of the people that say a good price cant be had I dissagree

I just got a 2008 with 25k miles MN6 1LT with NPP and a few other options for 31k!

 

Got my 2008 Z51 1LT about a year ago stock (NPP exaust and Z51 gears). Car felt a tad quicker then my buddies B&B bullet Axle back only 2005 LS2 3LT (I drove both). We raced, he beat me 2 times from a second gear roll. I am lost for words still. Just straight up pulled me from 3rd gear by like a car every time.

Maybe my car was spinning a bit in second but I don't recall it doing it. I shifted perfectly and my car weighs less then his and I weigh less then him. A B&B axle back isn't going to give his heavier 3LT LS2 35-40hp to beat my lighter 1LT LS3? I swear he has nothing else done to his LS2 unless the previous owner tuned it, but I doubt it. Makes no sense to me at all.

 

Last weekend, my buddy and I switched cars on a 150 mile road trip through the mountains of western NC. His car is an 05 Z51 Vert Manual, mine is an 08 Z51 Vert Manual. I didn't really notice a difference in acceleration performance and our gas mileage
was nearly identical, as it has been in numerous similar runs. I did notice a difference in the steering (possible larger steering wheel on the 05?) and the shifter throw on the 05 was further. The seats in my car felt more supportive and both cars are 3LT's. His car has the Firestone R/F's and mine has the Goodyear Supercars. The 05 felt like the tires were softer in the turns, but their grip was very good. We were driving aggressively; I got a 1.02 in my HUD - the highest I've ever seen in 28,000 miles. His car has 17,000 miles; mine 28,000.

 

Talking to the drag strip hounds in our club, I was told that typical times for the LS2 A6 were around 13.5 @ 106 mph, LS3 A6 w/performance axle around 12.7 @ 114 mph.

Some cars run faster, some slower, and different conditions make an even bigger difference; but on their strip those numbers are said to be a good comparison between the two engines.

Yeah, I know- your car is faster. But these numbers are an average of multiple cars on multiple days with multiple drivers.

 

If you plan on heavily modifying. I wouldn't fret over the difference. If your going to upgrade IM, Heads and cam anyway. -Wade-