Vortec: Too much engine? (Mileage questions)

Keep mind the display in the truck is the average of how the previous owner drove the truck. When I bought mine it showed 9mpg! After driving mine for a month I was averaging 12.5. And 15 hwy. I will say that the 6.2 will more than likely get better mileage towing than your previous 5.3 because it won't be working as hard!

Marc is right. Either it's a Y2K or newer or it's a 5.7. 99 Tahoes, Yukons, and Suburbans were the older body style. YukonXL and Suburban 2500s were also available with the 7.4.

davehultin wrote:
Hi,

I'm getting dangerously close up upgrading my 1999 Yukon with a 5.3 engine to a 2007 Yukon XL with a 6.2 engine. I was test-driving it today and saw the display list an average MPG of 11.5. Yikes! I'm second-guessing myself if I should have that much engine.

It's sole purpose in life will be to pull our camper, which is about 4500 pounds. I'm sure a 5.3 or 6.0 would be MORE than enough, but I'm wondering if a larger engine like the 6.2 will actually be more beneficial (in terms of mileage) when I'm pulling a trailer.

In other words, I know my 5.3 drops from 15 to 10 MPG on the road when pulling a trailer. Will the 6.3 have less of a drop because it's not working as hard? Will is also come in around the 10 MPG range?


This is a really beautiful truck, but I'm gonna kick myself if I get it and have to spend all my camping money at the gas station...:(

Are you sure it's a 99 and not a 2000? My 99 tahoe 5.7 tows my 7000 lb TT ok with lots of mods though and get 10 mpg. Not towing 20 mpg at 65 mph. At 2500 lbs less I would think it would do ok.

I have a Jeep Cherokee I6 that gets 22 mpg on the highway. Towed a 4500 lb TT to Death Valley and back, got 11.5 mpg. Have a 8.1L Chevy that gets 14 mpg on the highway and towed trailer to Death Valley and back. Same trailer same trip, got 9.6 mpg. Probably a lot of the difference would be that the truck itself weighs more.

I don't think you'll notice a lick of difference in MPG towing with the 6.2 vs 5.3. You will appreciate the extra WB of the XL though,and the extra power. I don't believe the 6spd came in the 07's but this could be wrong.

Campfire Time wrote:
The argument for smaller engines in trucks is often better mileage, but I've never been convinced that's true. We just sold a 2003 Trailblazer, much smaller than a 1/2 ton and it had an I6. Logic would make you think that it would get halfway decent mileage for a full framed mid-size SUV with that 6 cyl. engine. Its daily mileage wasn't any better than our PU. And only marginally better than our last Suburban.

You know, I've thought this as well. In the late 90's, my brother and I had identically sized/shaped Jeep Cherokees; mine had an I6, his an I4. Same mileage, his was just slower! I've known lots of guys who have gone for the smaller V8's in their trucks and had the same results as I did with a similar truck and bigger engine. When it comes down to it, you have to get the same weight moving, and it is going to take the same amount of energy, regardless of where it comes from.

Where I have seen bigger differences is in transmission, gearing, and stuff like that, particularly with highway driving. Our '10 Suburban does 15-20% better on the highway than our '05 (w/ 4.10 gears, 4 spd transmission), although the usual town mileage is about the same for both vehicles (in the 13-14 range).

would not be much different towing. Have heard the 6.2 can get not to bad empty mpg, if you are not racing it around. I tow 5000 pounds with my 5.3 373 suburban with 200,000 miles, and I am very pleased.

Yeah, I'd agree w/ APT. I don't think the AWD system is the way to go for towing. Last I considered it, it seems the tow ratings were actually lower than the non-AWD; just because it has a bigger engine doesn't mean it was designed with towing in mind.

The AWD is a gas mileage killer. I much prefer the selectable system found on the other GM models. You can get pretty much all of the same options on a loaded Suburban or YXL anyway. I may be biased, but that is the way we went.

I would just about guarantee that mileage of the 6.2, 6.0, and 5.3 will be within 5% of each other when towing -- they'll all be in the 8-10 range.

Good luck!

APT wrote:
My 6.0L 3.73 gets 8mpg towing at 67-70mph, 14mpg in my wife's mixed around town driving, and as high as 18mpg non towing highway.

What's interesting about this mileage report is that its not too far off from my 5.3 with 3:73 gears. My wife's around town driving is about 14 also. I just got it so we haven't done enough dedicated hwy driving to know what that mileage would be.

The argument for smaller engines in trucks is often better mileage, but I've never been convinced that's true. We just sold a 2003 Trailblazer, much smaller than a 1/2 ton and it had an I6. Logic would make you think that it would get halfway decent mileage for a full framed mid-size SUV with that 6 cyl. engine. Its daily mileage wasn't any better than our PU. And only marginally better than our last Suburban.

A big part of this is driving style. Jack rabbit starts and driving at 80 on the freeway are what eats gas. The way I see many people driving the full size SUVs and PUs, they have no business complaining about poor mileage.

My 6.0L 3.73 gets 8mpg towing at 67-70mph, 14mpg in my wife's mixed around town driving, and as high as 18mpg non towing highway. As I said, that's 2mpg better than my 2003 F150 5.4L over the 75k miles we owned it.

All wheel drive is not inherently bad. But the system mated to the GM 6.2L seems week. I have read about failures handling the 6.2L torque. The 6.2L is also all aluminum and IHMO not up to the task of 100% TV duty in high temps. I think the axles are also weaker in the SUVs than the half ton pickups GM put it in. 2007 is first model year for 6.2L, GMT900 SUVs, and the 6-spd. I have not heard too many first year troubles specifically, though.

I'd take an 8.1L 04-06 3/4 ton any day for dedicated TV. They are just almost impossible to find compared to 6.2L newer ones.