2024 Z71 mpg .. can it be this bad?

[SavageDad]

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

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.

 

[B-train]

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.

 

[SavageDad]

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 )

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.

 

[isp5190]

Makes me glad I got the diesel lol

Me too! 22-24 in town 30 hwy!