2024 Z71 mpg .. can it be this bad?

Joseph Garcia said:

Wife drives and the mpg drops? WOW! Opposite for me and my wife.

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Honestly I always drive when we go anywhere 99% of the time so I don't know what she's doing, but she's no Ricky Racer so I can't figure out how she always burns so much fuel on her short little jaunts.

Most engines are tuned to run richer during the break-in period. This helps seat the rings and keep excess heat at bay. Once that period is over (usually buried deep in the ECM with certain criteria that needs to be met), it will then run on your normally scheduled programming.

Another thing to consider is that there are multiple mechanical systems that are ALL breaking-in at the same time. The machining of new parts is quite phenomenal, but there is always the final in-use period where everything learns to play nice together. I'd give it a couple thousand miles and then see where you're at.

As stated by others: winter fuel and shorter trips don't help either.

Gearz said:

So you have a 5.3L 10 speed with 3.23 gears and semi aggressive tires with low miles. Do you race to the next stop light or drive at 80 mph, live in a cold climate, tire pressures low or high? Doesn't matter how I dive my 2011 Tahoe it always does 15 mpg all day unless on a long highway trip. Driving habits and above suggestions can make a big difference. Always use 87 octane and not premium fuel with a 5.3L. Let it break in but it won't help much ( it is what it is )

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Just my $0.02 but I switched to 91 on my 5.3 because it runs a surprisingly high (11.5:1 I think it was) compression ratio.

JayceeP said:

Makes me glad I got the diesel lol

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Me too! 22-24 in town 30 hwy!

We’re in southeast Texas, so not sure if the fuel is any different this time of year than summer … but yeah, we’ll hold off on any real judgements until after it hits 1k miles

And our Z71 has a small lift and larger than normal tires and wheels, 22” instead of the factory 20”

carsenault300 said:

We’re in southeast Texas, so not sure if the fuel is any different this time of year than summer … but yeah, we’ll hold off on any real judgements until after it hits 1k miles

And our Z71 has a small lift and larger than normal tires and wheels, 22” instead of the factory 20” View attachment 442806

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Uhhhh yeah, that is part of you issue. The rims and tires. Don't be surprised if your hwy mileage sucks as well.

Yeah, I mean not sure the 22” wheels is the issue but rather the mud tires that are on it. That and a lift would have to be your culprit and would explain why your highway mileage is suffering.

JayceeP said:

Yeah, I mean not sure the 22” wheels is the issue but rather the mud tires that are on it. That and a lift would have to be your culprit and would explain why your highway mileage is suffering.

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I'm sure those 22's weigh more than the 20's which won't help city mileage.

SavageDad said:

Honestly I always drive when we go anywhere 99% of the time so I don't know what she's doing, but she's no Ricky Racer so I can't figure out how she always burns so much fuel on her short little jaunts.

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My ex use to tailgate people and she would have one foot on the gas and one on the breaks and she would make her kids have motion sickness from all the hard stopping and acceleration she was doing, plus burning a lot of gas and break pads. I politely explained to her how giving the car in front of her a little more space would be better for everyone. Also tough her how to use cruise control when ever possible.

There are very few upgrades that will increase your MPG.I know you say you drive the same, but did you ever get on the gas just to see what its got? Just one hard acceleration or passing someone will eat your mpg. Is the gearing the same? Also use your gps on your phone or nav to make sure you are going the speed your dash displays.



The only real “upgrade” you can do to improve MPG is lighter rims/tires. Might google the weight difference between what it has on it vs what you had on your old ride. I just bought new tires on my truck that are 15 lbs lighter each, than the old ones, and I gained 4mpg. Just depends on who you want to pay, rim company or gas company. Also the sooner you buy lighter rims, the more money you will get back from them if you go this route.

Number 1 thing to improve you’re Avg MPG is let off the gas sooner when slowing down for a turn or stop. When not in heavy traffic, the more you coast the more miles you get per gallon esp exiting the freeway. Give people in front of you more room so you are not breaking every time they are, instead just letting off the gas and coasting until they are done texting and resume the speed limit.

Number 2 is lighter acceleration, you can watch your instant mpg and see how much peddle to use to get your best mpg. There are also spot where you can let off the gas and it will switch gears sooner, which should get you better mpg. Getting up to speed faster does not save you gas, you can’t get back gas you burned. Find your peak hp/torque and try to keep your rpms there when accelerating.



Using Cruise control can help a lot too, Some people might tell you they can get better mpg in hillier area’s than using CC, which is generally true, but you should also be able to change your CC accelerations aggression level which will keep it from doing hard accelerations up hills. Hopefully soon they will put in an angle parameter into the CC calculation.