2014 5.3 vs 6.2 MPG while towing?!

biggblokk · March 2, 2014

I'm ordering a 2014 Sierra tomorrow. SLT All terrain plus... can't decide on the engine. The 5.3 is fine, but the 6.2 is just awesome fun to drive. So in attempt to make both sides of my brain happy, I'm curious if the 6.2 might get better MPG while towing my 3500# Ranger Bass boat? Or at least similar MPG? Theory is bigger engine = less RPM and work to do the same job. Any real world towing numbers on either engine? I usually set the cruise at 74mph. I want to avoid the gear hunting issue my 2008 Suburban had on mild hills in WI... very annoying. Oh, I'm assuming 3.42 gears with the 5.3, not sure on the 6.2, would love suggestions, thanks in advance!

bdbake01 · March 2, 2014

6.2 will get you 3.42's standard unless you go NHT/max towing which gets 3.73's. Which I don't think you can get w/ an AT? Somebody correct me if I'm wrong. If you're planning to tow, stick w/ 3.42's or higher regardless of engine choice.

Johnnyee · March 3, 2014

I'm ordering a 2014 Sierra tomorrow. SLT All terrain plus... can't decide on the engine. The 5.3 is fine, but the 6.2 is just awesome fun to drive. So in attempt to make both sides of my brain happy, I'm curious if the 6.2 might get better MPG while towing my 3500# Ranger Bass boat? Or at least similar MPG? Theory is bigger engine = less RPM and work to do the same job. Any real world towing numbers on either engine? I usually set the cruise at 74mph. I want to avoid the gear hunting issue my 2008 Suburban had on mild hills in WI... very annoying. Oh, I'm assuming 3.42 gears with the 5.3, not sure on the 6.2, would love suggestions, thanks in advance!

I've had my Silverado 6.2L/Max Tow (3.73 gears) for about 3 weeks. I have towed my 6300 pound trailer for about 140 miles. I had a strong head wind, and at the end, my mileage was around 10 mpg. Now, I only have a 1000 miles on my truck, and i cruise around 60 mph. But the point is, my mileage wasn't any worse than my old 5.3 with 3.42 gears. If I had it all to do over, I would still pick the the 6.2 and the 3.73 gears. Good luck on your decision.

music · March 3, 2014

Fuel economy while towing with a gas engine is almost independent of the size of the motor, except for the older big blocks (which were worse). Running higher rpms on a smaller motor can actually be more efficient than low rpms on a bigger one, but I think everyone prefers towing at lower rpm, given the choice. The bigger motor has more reserve in the mountains too.

For me, I tow a ~7k lb camper (loaded), and would lean heavy towards the 5.3 in the current gen (preferably, with the max tow... but not required). Not because I don't like the 6.2, but because I'm not interested in the LTZ / SLT trims.

seamonster · March 3, 2014

Fuel cost overall not necessarliy towing will be about 20%.

10% more for the premium and according the gm's rating another 10% in mileage diff.

I figure the difference if i drove 15000 miles per year to be about 5-600 dollars per year.

I dont think the 2K to get the 6.2 is bad because you would get much of that back on

resale. There is some cost to the 6.2 but it sure would be fun. I know I want one.

I will prolly end up with the 5.3 though

Biggest problem with the 6.2 is lack of availability--they could sell on ton of them if

there were more on the dealer lots. Government fuel regulations perhaps???

redwngr · March 3, 2014

I'll bet it has more to do with when the tooling to build it was completed.

No doubt they wanted the higher volume engine available first.

Still haven't seen a 6.2 in Ontario. (although it can now be selected in 'build and price' on gm Canada's website)

biggblokk · March 3, 2014

Funny... I was just making a spreadsheet with cost of fuel over three years...$1500 was my number, very similar thought process! FYI - no max towing in the all terrain, suspension conflicts... No problem for my towing needs, just FYI for others reading the post. After a lot of reading (truck trend has some good info) I'm thinking i will order the 6.2. It's only 1-2 mpg, the fun factor and advantage towing through hilly areas offset it in my mind. Plus, fun to say its a corvette based engine. I would love to hear any real world numbers on the 6.2... Lots of info on the 5.3s, could use more on the 6.2.

onceagain · March 4, 2014

I will agree with the person above. I took delivery several weeks ago and pull my 24 foot bay boat w/300 Yamaha with a hard top that picks up a lot of wind. I guess loaded its around 6000lbs. My 2013 6.2 3.42 did about 8 mpg towing and always was hard to pull. What im saying is it was geared to high and couldnt find a good spot to pull. Kept down shifting. So I ordered a 2014 6.2 w/3.73 NHT and it made a large difference. I am getting 10 mpg but large difference in the way it pulls. But pulling a bass boat I would say you would be fine with 3.42

pm26 · March 4, 2014

When you write a check for a 50k vehicle are you really going to be concerned about losing 1 MPG for a ton more power?

Except not too many people write a check when buying a truck. Most people finance vehicles in this price range. When you write a check for $ 50k , you think twice if that truck is really worth that much money. Spending that much is a lot easier when you spread the payments over 72 months with little or no money down. Been there both ways and that is my experience. .

Ulukslo · March 5, 2014

If you are even discussing pulling get 3.73s!!! Dont let some one tlk you into 3.42s!! Gear always helps pulling and the lower gear will help in town mileage and life of transmission!! Im pulling with my truck all the time and I have 3.73s!!! They are killer for pulling for playing and they assist in V4 mode also!!

ShotgunZ71 · March 5, 2014

If you're set on a 6.2 engine, get the 3.73 if you're towing much. If you like the 3.42 gears, get the 5.3 engine. In that gearing, the 5.3 outperforms the 6.2 for payload and towing. You'll likely not see a great increase in mileage while towing, though. Either way, you should be fine pulling within limits of a half-ton truck.

Bcp7272 · June 3, 2014

Pulled my RACECAR (5klbs) about 375 miles this past weekend. Was averaging 14 while on the highway. Dropped to 13.5 overall. 5.3/342 2wd crew cab/short

Green 1364 · June 18, 2014

I have a 2014 GMC Denali 5.3 MPG is horrible. I only have 600 miles on it and it has only averaged 14 MPG. Anyone else having the same issue?

Sooperdave · June 18, 2014

6.2L 3.73 here... I pulled a 3500lb bay boat/trailer, run 60-70 depending on area, and was rewarded with 13mpg. Hit multiple lights on way back as we had to take route off the interstate. I was very happy and she pulls quite well!

Last C5 · June 19, 2014

Funny... I was just making a spreadsheet with cost of fuel over three years...$1500 was my number, very similar thought process! FYI - no max towing in the all terrain, suspension conflicts... No problem for my towing needs, just FYI for others reading the post. After a lot of reading (truck trend has some good info) I'm thinking i will order the 6.2. It's only 1-2 mpg, the fun factor and advantage towing through hilly areas offset it in my mind. Plus, fun to say its a corvette based engine. I would love to hear any real world numbers on the 6.2... Lots of info on the 5.3s, could use more on the 6.2.

Three 250 mile round trips over the same route towing 4K (race car & aluminum car hauler) with my LTZ 4X4 Double Cab 6.2 that has 3.42 gears. First trip 65 mph got 14.9 overall average, second trip at 70 mph got 15.1 overall average, and the third trip at 70 mph in pouring rain and wind got 15 overall average. Getting 19.9 running empty at 70-75 mph. So far I only have 1370 miles on the truck and I'm hoping it'll get a little better when it's fully broke in.