[Silxshane]

I don't drive my sierra much but it's only getting 14 miles to the gallon. I purchased the truck new and it has the 5.7 engine. Can anyone with a similar truck comment

[CaptainRich]

I don't drive my sierra much but it's only getting 14 miles to the gallon. I purchased the truck new and it has the 5.7 engine. Can anyone with a similar truck comment

That's about right.
I've had two Silverados, both extra cabs and both with 5.7L, one a '95 and an '03.
They have been fantastic trucks and I've made them earn their keep but the fuel mileage (or lack thereof) is why I let them go. Maybe if I didn't use the truck as often (you say you don't drive it much) I'd have kept the '95. The few repairs that I needed done I've always used the dealer for parts. The important part of that is if you buy the parts through them. that replacement parts usually carries a lifetime warranty to the original buyer on both the A/C compressor and alternator.
These are strong work trucks right off the dealer lot and will pull stumps if you asked 'em to but the mileage isn't for anyone who commutes.
Today, my current daily driver and commuter is a Tacoma Prerunner SR5 with the 6 cyl and 4 doors. Better fuel economy plus it fits my garage where neither Silver would come close to fitting. I don't tow too often but can still pull everything I pulled before.
Before you seriously consider a different vehicle, you may want to consider the recovery time from the purchase price as compared to what you'd spend on gas for the next lifetime of either truck to see if it's worth the change. I was lucky here in Florida since I had recently renewed my old truck registration and was allowed to swap it onto the Taco for a very reasonable fee.