Fuel Mileage on '07-'08 GM pickup

[iffwalleyes]

Guys I am thinking about sending the duramax down the road and hoping back into the 1/2 ton version again. Just wished I didn't have to go with that little sawed off box on the 1/2 ton crew cab that they are putting out there. What I am curious about are they getting the milage advertised? What can one expect for a 5.3 one either a GMC or Chevy. I had one in my '02 silverado and it never got better than 15. I now there is alot that has changed in them. Do they get close to 20 on the highway as they claim?

[Hookmaster]

I know what you mean about the 5 foot 9 inch box. I have a 2004 Z71 Crew Cab and the loss of length in the box is noticable but worth it for my kids in the back seat. When I was breaking it in the electronic gauge would say 18-19 mpg. This was at 45-50 mph. If I go 55 mph today it says 17-18 mpg. At 65-70 mph, it says 16-17 mpg. These are all without towing. The trucks today are supposed to do better but I don't know about them.

[BoxMN]

Just a suggestion, but don't you guys have to talk about what axle ratio if you are talking mileage? I think it comes in a couple and that will make a big difference. Maybe I am wrong....

My brother has an 07 and it is a great truck, crew cab, but that little box is, well, tiny.... I think my '98 short bed (3.73 ratio) is kinda small, but his is ridiculusly small... but his seats kick butt!!!! I want him to drive if we don't need to bring anything He gets ggod mileage not towing, about and honest "do the math" 18-19 MPG, but I am not sure what towing long distance brings. Nice truck though!!!! But I, personally, could not have that short bed.

Good luck!

[Walleye Guy]

I have a 2007 GMC Sierra SLT Crew Cab with the 5ft 9 inch box. I wish the box was longer but I have just learned to pack a little more efficiently. So far its been a great truck. I am addicted to the Bose/XM stereo combination! It rocks.

My truck has the 5.3L with the 8 to 4 cylinder deactivation. In the cities I average around 16.4 MPG. That is according to the fancy little computer. On highway trips I usually average around 18.5 MPG if I am not pulling a trailer. I have had trips where I got over 19 MPG.

One thing that seems to help the highway mileage is to kepp the RPM's at 2000 or lower. 2000 RPM's will still get you around 70 MPH depending on the terrain and the wind.

I would highly recommend the truck.

[marine_man]

I think the biggest problem with the shorter box is that you can't close the endgate with a otter magnum lodge fish house... that's where I really have a tough time with this decision...

marine_man

[JonnyBfromHutch]

Good topic to discuss. I've been driving my '07 Silverado 'Classic' (older body style) 5.3L for 20k miles and have been a bit disappointed with the mileage, especially running E85. I've found that the electronic mileage maps pretty well with actual, so I quit doing the math and just check the gages when I'm interested.

I can get 17 on 89-91 octane in my normal hwy driving in the 60-70 range, and with E85 that goes down to 15 or so. City is 14-15 on 89-91, and 12-13 with E85.

Pretty sad the E85 can't be somewhat better. Hopefully the next generation of engines will be more efficient.

[Walleye Guy]

While some may argue running on e85% is a good thing from a dependence on foreign oil perspective, e85 does not provide the same amount of energy as standard gasoline and your vehicle needs to consume more fuel to do the same amount of work. As long as E-85 costs 20% less that regular unleaded gasoline its probably a wash from a cost perspective.

As far as a fish house fitting in the back of the shorter bed, I did quite a bit of research and the biggest flip-over fish house I could find that would still fit in the box and allow you to close the tailgate is the Otter Medium. I picked up one in the new Ice Camo because of this.

[Dave S]

I have an "08 Silverado with the 5.3L with the Active Fuel Management system. I use the truck to commute 80 miles round trip each day for work and can average 14 with E-85 and averaged 18.5 mpg with 87 octane unleaded going up to Ely a couple weeks back.

One thing to remember is the 20 MPG rating is for the 2-wheel drive trucks, not 4x4. It's in the fine print in the brochure.

I suspect that most vehicle MPG rating are based on 55 mph speed limits on flat land, and maybe a slight tailwind.

So far I love my truck and finally put my Honda Rincon into the box today. I'll have to get used to either pulling a trailer or leaving the tailgate down.

My biggest problem with the truck so far is staying out of the 315 hp and the exhaust note. This truck sounds better with the stock exhaust than the HEMI equipped Ram that I had 3 years ago.

One more quick note, I figured with my average mpg between E-85 and regular unleaded, I need a 70 cent difference in price before I break even in "cost per mile".

[fishin58]

Exactly what we have heard from our Customers Lep7MM and Walleye guy. To a T that is what we hear. You are also right on with your E85 comments that is the break mark for burning E85. Those numbers are tough to come by for different parts of our state. South Dakota has some places with a dollar difference. 99% of the 1/2 ton trucks we send out of here have 3.73 gears with 17 or 18 inch rims. Some guys get the 4.10 gears if they are looking to pull more or if they have 20 inch wheels, some guys swear by there results with this combo. They used to offer 3.42 but that was not any good for pulling or hills or anything in my opinion.

[fishin58]

Also the box...the main reason for the box size is for the average size of your garage. If you added another foot would you be able to fit it in your garage?? They were looking out for the everyday consumer, afterall these crew cab trucks have pretty much become the family truckster. The Extended cab still has a 6.5 ft box. They are the same wheel base and overall length asthe crew cab.

[iffwalleyes]

 Originally Posted By: marine_man

I think the biggest problem with the shorter box is that you can't close the endgate with a otter magnum lodge fish house... that's where I really have a tough time with this decision...

marine_man

No the real problem is you know that you have a 6.5' box and that an otter fits in it. Since we fish together often you know that you are going to have to drive all the time. But I you know you like riding in that crew cab much better than an extended cab too you tall bugger.

[cribbageboy]

It's just terrible that in this day and age, that vehicle manufacturers wont take the time to make more fuel efficient vehicles. We all know they can do better, they just dont want to take the time. This is ONE time where I feel the government needs to step in and put a little control on it. I dont know maybe no lower than 23 cty on a V8, 28 cty on a V6, and 32 cty on a 4 cylinder. The whole thing sickens me. Good luck on picking the right truck though.

[Dave S]

cribbageboy,

I see your point. It does seem like we should be getting better mpg out of the new breed of vehicles.

But I look at it this way. I bought the truck knowing what I was going to be getting for MPG. Also, compared to the '94 2wd GMC Sierra that I had with a 305, I get better MPG per horsepower with my '08 Silverado 4x4. If I remember correctly, I think the GMC was 205 hp at that time and the new 5.3L in the GM trucks is getting 315 hp. The trucks are simply far more capable than they were 10-15 years ago.

Yes the technology is there, but I think there will be a HUGE push for better economy in the coming years. GM already has full-size hybrid SUV's so we're starting to see the beginning of it now.

[cribbageboy]

I guess if you look at it like that.......

I did read an iteresting article in Minnesota Conservation Volunteer (January-Febuary '08) The National Resources Defense Council published a report that states that the US consumes 146 billion gallons of fuel for transportation (100% of that is gassoline). By the year 2050 it is projected to be right around 240 billion gallons. They want only 20 billion gallons of that to come from gasoline, and 77 billion to come from biofuels. The equivelent of 42 billion gallons of gasoline will come from electricity (fuel cell vehicles, etc...). They estimate that 77 billlon gallons of gasoline will be saved by changing the fuel efficiency of passenger cars and light trucks from around 26 mpg now, to 52 mpg by the year 2050. They also plan to lower Vehicle Miles Traveled by using trains, and buses more often. Now 2050 is 42 years away, and for some of you (however depressing it may be) might not ever see it. Being that I am only 18, I hope I will, and nothing pleases me more than reading about big plans for the future.

[Dave S]

one thing that can happen immediately to reduce our fuel consumption is to lower the speed limit back down to 55-60 mph.

I traded a Toyota 4Runner for my Silverado and at 55 mph on flat ground, I could get 26 mpg with a 245 hp V6. Note this vehicle was only rated at 21 mpg on the window sticker.

Now take into consideration commuting speeds that average 70-75 mph, winter months, winter blends for fuel, and now my MPG has dropped from a potential 26 to 17 mpg. That's a 33% decrease.

Just imagine if every vehicle could save this much in economy beginning tomorrow.

Sad thing is, it may never happen and I value my life too much than to drive 55 in a 65 mph zone (road rage) if you know what I mean.

[rowdyf]

'08 GMC 5.3L

3.73 rear end

Active fuel mgt

E85 capable

15-16 this winter with warming up, etc

17-18 last summer/fall

[cribbageboy]

My uncle mixes E85 and regular unleaded. He gets decent gas milage, and doesn't break the bank at the pump. He drives a 1990 Cadillac Deville. Deffinitly not rated for e85, but he has been doing it since the stuff came out, and no problems so far.

[fishorgolf]

Cribbageboy,

I don't think the reason you don't see 30 mpg full size trucks is because the manufactures "won't take the time" Don't you think if chevy/ford/dodge came out with a 30 mpg full size truck that had the power people want they might sell a few?

[iffwalleyes]

Government and manufacture was not the point to my post. Looking for actually fuel mileage facts of the full size silverado or sierra pickups so let please keep it at that. Thanks

[cribbageboy]

By "won't take the time", I mean that truck manufacturers are too busy coming up with better looking, and overpowerful trucks, that they "don't think it necessary" to take the time to make a high mpg truck. They are thinking "well we have a car on the market now that gets 45 off the lot, if someone wants good gas mileage, they can buy that". Now I see your point but I CANT help but think that in the year 2008, with all our current technology, they can't think of one way to get better gas mileage on trucks. Sorry Iffwalleyes, I promise I wont bring it up again.