MPG WITH Z71/4x4

A fella at work told me he gets 18 mpg average with his 02 Avalanche Z71 (6.0 liter)with no major mods. What are you guys getting with the 5.3 and 6.0 liter?


I have an 02 Silverado Ext. Cab Z71 with K&N air filter, and I average 15-16 mpg with normal driving/tailgate down on the highway.

Thanks in advance.

mpg is up to you, if you drive like mario andrety your mileage will show it if you drive like the little old lady from passadena your milage will be better, i have several different vehicles, 86 fiero se v6 get 25 mpg around town, 92 f 150 king cab gets around 15 city 16 or 17 highway, 94 burban 18 to 20 highway, and 2 full size ford vans that never get more than 16 mpg no matter where you drive or how you drive. like i siad it depends on how you drive, lend your friend your truck and take his for a week, i bet you will see that it is the way you drive not your truck. trucks are made to work not get great mpg. my wife gets better mpg than i do unless shes hauling the four horse stock trailer. if you think its not you try a full tuneup.

Just got back from vacation, 03 AV, 5.3L, 4x4, 19.8mpg @ 70mph Lansing Mi., to Kingston Ont.
Local city driving 14.2 - 16.8 avg. depending on the foot !!

I just bought my Avalanche; 2002 Z71 5.3L Vortech with 57,000 miles. I am the 2nd owner. I purchased it in Idaho where I am from, drove 700 miles to portland and averaged about 18 MPG Highway. No mods except 22" Rims with 305/45/22 Nitto 420's. Then I drove home 1000 miles straight down I-5 to L.A. where I live now and got about 17 MPG. I was pushing a major head wind though. All and all im really impressed.
Just my 2 cents.

I've got a 2002 z71 4X4 1500 with 70K miles....I get 15 city and 17 Highway when I drive like a granny.

A fella at work told me he gets 18 mpg average with his 02 Avalanche Z71 (6.0 liter)with no major mods. What are you guys getting with the 5.3 and 6.0 liter?


I have an 02 Silverado Ext. Cab Z71 with K&N air filter, and I average 15-16 mpg with normal driving/tailgate down on the highway.

Thanks in advance.

First off there is no such thing as a 6.0 liter Avalanche unless someone did an engine swap. I do know of a couple floating around but they are rare. Unless youare talking about the Escalade EXT. That does come with the 6.0. As for the Avalanche there are no engine options. For now. Mid year 2007 they are going to offer a 6.0l optional engine but if we are talking about the 02-06 the only engine offered in the 1500 is the 5.3 liter and the 2500 gets the 8.1.

As for mileage I have a 03 Z71 1500 with the 3.73 rear end. When it was bone stock on a road trip I was able to get 23 mpg out of it. That was setting the cruise at 60 mph and leaving it there. It is pretty rare but that is about the best I have seen in these trucks. I think I averaged in the 14 range normally because I drive in the city. Since then I have added a K&N drop in filter and a FlowMaster S40 Cat back exhaust. I now get 15.5 mpg average in the city while my highway has dropped slightly. Around 20-21 is what I normally get. Although I have been driving faster on the latest trips so that explains that.

Like mentioned speed has a lot to do with it along with how you accelerate.

A fella at work told me he gets 18 mpg average with his 02 Avalanche Z71 (6.0 liter)with no major mods. What are you guys getting with the 5.3 and 6.0 liter?


I have an 02 Silverado Ext. Cab Z71 with K&N air filter, and I average 15-16 mpg with normal driving/tailgate down on the highway.

Thanks in advance.

Food for thought: Mythbusters did a test and found that driving a truck with the tailgate down actually LOWERED the gas mileage!! They explained and showed why, it had something to do with the way the tailgate affected how the air flowed over the truck and bed.

Food for thought: Mythbusters did a test and found that driving a truck with the tailgate down actually LOWERED the gas mileage!! They explained and showed why, it had something to do with the way the tailgate affected how the air flowed over the truck and bed.

This is true. As you build speed the air creates a bubble in the bed area when the tailgate is up. This bubble of air causes the air comming up over the cab to flow right up and over the tailgate. With the tailgate down the air comes up over the cab and slams down on the bed. This causes more drag and reduces fuel economy.

Very well explained!! I forgot exactly how they explained it, but you hit it on the head!!