Hey guys! I have felt the Blazers range has been really lacking lately, and upon searching up the range others are getting I am a bit concerned. So I have some figures here from my last fill up, 208.8km took 42.9L, doing the math that's 20.5L/100km or about 12 MPG. Another concerning thing is the gas gauge was right at 1/4 when I filled up, and it only took 42.9L, which is missing about 15% of what the gauge was showing. Everything is pretty much brand new on the truck, engine, driveline, air filter changed recently etc. The things bringing my MPG down over a stock blazer are the roof rack with the spare mounted in it, and the oversized tires. I have a P0420 code which I have had for awhile, but I have tested my exhaust for a restriction and there is none. What do you guys think? I'm thinking I may replace the o2 sensors and see where that puts me. I'm in the process of choosing a rooftop tent now and fuel efficiency is definitely a factor because even a 1-2 mpg hit will be a lot right now!

 

Hi Zack,

We get 14 mpg on the average when not straight on the highway. No big tires - no roof rack. Not much better than you. You could check for a sticking brake caliper, but mostly you are simply pushing a tall brick through the wind. About all you can do is slow down.

One thought..... with the P0420 setting, the PCM might be preventing the TCC from engaging. That could cost you a little mpg. I know this type of thing definitely happens whenever P030x codes are present. Don't know about P0420. Can you see the tach drop when TCC engages under light throttle at about 43 mph in 4th gear.

My gas gauge is not accurate either. Drops like a rock once you get below 1/2.

Getting ready for your trip?

 

I lost mileage when I added a roof rack and storage box on top. This added drag and then there is the extra weight if my revovery gear in it. I also carry extra weight in my truck with tools etc., and in the winter two sets of tire chains.

Putting on larger tires can affect your mileage calculations too. With my 30" tires, my actual speed and thus the actual distance traveled is about 5% more than indicated on my speedometer and odometer.

All that said, your mileage does sound low. On the highway cruising at 65 mph, I can almost get 16 mpg, perhaps 17 mpg (corrected for the tires).

Around town, 12 mpg is good!

 

Thanks for the clarification guys, I will continue tracking the MPG next time I fill up and see how it is. I will say that it's pretty much all city driving to and from school every day. I think since you're getting 14 MPG with a stock blazer, 12 MPG is realistic for mine. Though I was reading on here someone saying they can go 250 miles on a tank, with 31's on, I would love it if my blazer could do that! I'll be planning a smaller trip to Banff as a test run before the "big trip" once I have the blazer all complete and I'll be able to get an accurate highway reading with all the additional stuff as well. Of the many things for the trip, I have been thinking of a 3 row rad and with that, electric fans, which should also improve mpg.

On the topic of getting the blazer ready for the trip, I'm slowly making progress. I have the battery box all designed with how I will mount it, along with a mount for the battery (planning to make my own strap using 2 bolts bolted to the floor, and a piece of steel across the top). I also have everything needed to complete the battery box now (battery, charger, fuse box, breakers, monitor, 0 awg wire, etc), I just need to get some plywood and speaker carpet then put it all together. I'm also looking for the swing-out tire carrier that came on the ZR2 right now, the only one near me at pick-n-pull is in Arlington which is across the border and my passport is expired! On ebay they are selling for upwards of $400 which is ridiculous, I was at my local pick-n-pull last summer and was looking at one going "no I don't need it", I'm really kicking myself for that right now. The tire carrier will be heavily modified to hold a larger tire and jerry can, to remedy the cracking body panels I will take off the lower body panel mount and make a mount directly to the frame where the rear bumper bolts in. Lastly, I'm trying to decide between two roof top tents, either a 2 person soft shell tent, or 2 person aluminum clamshell. I'm leaning toward the hard shell for the MPG savings, I'm thinking either way I could build a new rack and mount it as low as possible to the roof. I will update my build thread as I get working on the battery box!

 

12 MPG isn't terrible with 31" tires and a roof rack. Especially if you're loaded with gear. I did a couple 500Km highway trips last summer with my Sonoma loaded and pulling a 3000lb cargo trailer and averaged ~12MPG (19.7L/100Km). I'm running 32" tires with 4" lift.

Your mileage is also going to be affected a lot by the terrain, and your right foot.