Avalanche/Chevy Trucks - 4 speed vs 6 speed

Anyone have any insight on the differences (gas milage, towing capability, performance) between the 2007 and 2009 Chevy Trucks? I believe in 2009 they went to a 6 speed transmission, where as the 2007 still has the 4 speed. I'm considering upgranding my 2004 Avalanche to a newer year, but am not sure if it's worth spending an additional 7k or so and getting a 2009 in order to get the 6 speed?

Also, are there any gear ratios to specifically go for?

Lastly, does the Z71 do a little bit better for towing? I think the suspension is stiffer on the Z71s?


Right now I have a 2000 XStar and the Avalanche does just fine towing it, but this weekend we'll be picking up a 2011 SAN 230. If my 2004 does okay towing it, I think I would like to stick with another Avalanche (just a newer one), but if it struggles I may consider getting a 3/4 ton diesel, or getting an Avalanche with a 6 liter.

Thanks for you input!

I actually just went through this to an extent. I had a 2005 avalanche with the 4 speed. To make a house deal work I ended up trading it in on a truck for my brother. He got an 09 GMC Sierra with the 6 speed. Let me tell you the 6 speed makes WORLD OF DIFFERENCE! He averages over 20mpg on the hwy and 16-17 in the city. (his has the 5.3L in it) He also got 13mpg towing our A22 60 miles down the interstate. Keep in mind this is all at 5k+ feet of elevation due to us being in the Denver area. I have driven the truck a bunch of times and man the 6 speed is incredible. More get up and go when you need it. More MPG if you keep your foot out of it. Shifts so incredibly smooth!!! I am going truck shopping in the next 2 weeks and the 6 speed is at the top of my list of things I want. Also the 6 speed is rated to tow at around 10k pounds and the 4 speed is rated at 7200lbs that is with the 5.3L engine.

I am a fan of the Z71 suspension upgrades personally.

Towed an Enzo 230 with a 4-speed Avy. Over flat ground got 11 to 13 mpg. Lost the tranny at 67,000 miles over Kentucky hills. Still have the truck, but it will probably be my last Chevy.

I have owned 7 different chevy trucks. Ford has really stepped up there game. The 5.0 v8 has more hp and torque than the 5.3, and better gas mileage too. This year i bought a ford Raptor, love the truck, but the mpg is14 combined.

At the moment I currently own a 2000 Silverado 5.3, a 2003 Tahoe 5.3, and a 2007 Avalanche 5.3. All have 4 speed automatics with 3.73 rear axle gears. I sure wish the Av had 4.11s, it. a bit more sluggish than the Silverado and Tahoe. I expect uphills to be a challenge but I still prefer the 2007 over the older versions. Part of the sluggish response might be the drive by wire plus I am pretty sure it's heavier. The 4 speed tranny's (4L60E) have undergone some changes over the years, I am pretty sure my 2000 has a lower 1st gear ratio so it feels faster off the line. The flip side is that it cannot shift from 1st to 2nd and maintain speed while towing up a steep grade (might be the computer controlled torque limiter causing this issue). If you are rolling it will maintain speed but if you get much under 4k it can't hold or increase speed. Most of the 6 speed trucks have the 3.42 rear axles, that's why they get better mileage. I keep don't let any of my trucks shift into 4th while towing, that 's what kills these tranny's. It seems that the 6 speeds are better in that regard. I get 16-17mpg in the Silverado, about the same or 0.5 better in the Hoe, and 15-16 in the Av but I also tend to drive the Av faster and it has 20's so everything considered the Av is probably more economical. I get 10-11 towing at 65 on a mix of fwy, country, hills and flats with both older trucks, have not towed with the Av yet.

Night and Day the 4-speed on flat ground is ok but does not cut it in the hills of KY or TN.

Over the past 10 years of towing boat from Ohio to TN, I have used a hand full of different chevys
2003 Chevy 1500 HD with the 6 liter and 4-speed
2006 Chevy 2500 HD with the 6.6 Liter Diesel and 6 -speed
2007 Chevy Suburban with the 5.3 and 4 speed, towed the boat down to the lake used the QX56 to tow back, did not like the trans temp in the 230
2009 Chevy 1500 with the 6.2 liter and 6 Speed does almost as good as the Diesel, but fits in the garage.

I have a 09 Sub w 6 speed, 1500 4x4 with the Tow package and stock tires. It does pretty darn good on gas 12-13 around town 18-19 hwy and is great to drive. Towing hills is a differant Story. I had to have an additional Tranny cooler added to because of HIGH tranny temp 275 deg ( YES 275 deg). I still see high Tranny Temp 239-242deg range when towing up hills from So Cal to Lake Mead. The only way it will make up the hills is if I put it in 3rd and hold the rpm 3,500 or higher, then it will go at 50-60 mph. Then you pray that no one will slow you down becuase once it bogs down it will never make it above 40-45mph. Mine has 3.42 Gearing wishing it had 3.73. The Gearing in the Truck just seems wrong 5th and 6th are both over drive gears. I could understand if I was towing a 24foot Wake monster but i'm Itowing a Sanger v210 (2,900 lbs). Wishing I would have bought a another Ford.

Well, picked up the new 230 this Thursday, and unfortunately, I was not impressed with the way the my 04 Avalanche performed. Just seemed to be pretty overworked when getting up to highway/interstate speed of 70 mph, and then keeping that speed going up minor inclines. I didn't think there'd be a whole lot of difference between the 2000 XStar @ 3300 pounds on a single axle trailer vs the SAN 230 @ 5000 pounds on dual axles, but man there was.

I think if I were going to always be staying in town just going 30 mph or less, then I'd be totally fine. But there are chances (depending on the wind) that I'll be traveling down the interstate at about 70 mph, 30 miles round trip, 2 or 3 times a week.

My current Avalance has the 5.3L with a 4 speed, 3.73 gear ratio. Will I notice a big difference in towing going to a 5.3L with the 6 speed, 3.42 gears? This is also my daily driver (30 miles round trip), so it sounds like I'll get better gas milage in that aspect.

Any other engine/tranny/ratio combinations I should try to find on the Chevy's?

I am in a similar situation. My 02 Yukon with 5.3L and 3.73 gears did fine with my old X-2. My new SAN 210 is more of a load and I am looking at upgrading.

I like GM trucks but the only gasser I would get is the 6.2L with 3.73 gears. IMHO GM lost me when the dropped the 3.73, 3.42 is what you get in the 5.3. I think you would be disappointed with the Avy 5.3, 3.42 but the six speed will help.

So I am looking at Fords, V-8 5.0 and the Ecoboost V6 with 420 Ft Lbs at 2500 RPM/360 HP.

Or I may keep my Yukon since it does the job. Maybe GM will get there act together and put a proper gear ratio in their 1/2 ton trucks?

I don't think the 4 speed vs 6 speed issue is going to make nearly as much of a difference in your towing experience as getting the right gears will.
My 05 Av with the 5.3 has the 4 speed auto with 4.10 gears & it tows my Vride fine. We just made a trip to Hells Canyon last summer, loaded up, 4 adults in the truck, and the thing never had to use 2nd gear going up hills, or dropped under 50 mph at all. Overall we finished at 12 mpg over 900 miles.
Get the right gears if your going to use it for towing.

As for the Z71 package, all it is is a skid plate & some Bilstein shocks. If you find a regular Chevy truck, with 4.10 gears, and the rest of the truck is good, then upgrade the shocks & buy a skid plate online. My Av has 105k miles & over 2500 hrs on it, and the Bilsteins have long been replaced with Monroe Reflex gas shocks. And I stripped the stupid decals off the truck too.