biglg

I am rolling on 24's and averaging about 24 and that iswith a supercharger, underdrive pullies, exhaust, aftermarket cam, and a tornado air funnel!

Big D

I run e-85 (higher octane plus I much rather sendmy $ to NebraskathanRyadh). DIC tells me 14.1 to 14.3 mpg. I ran a few tanks of Ryadh's finestand my best mileage (again overall) was 17.5. I have a K&N air filter, magnaflow exhaust, and mobil 1. Considering the big V-8 and weight of the vehicle and comparing it to the mileage of many mid-size import and domestic SUV's I still think the Tahoe, for its class, has pretty acceptable mileage, but then again, that is the opinion of a die-hard tahoe fan.

engine2

The best way to get the most accurate MPG reading. The DIC is just an estimate.

73shark

Is that one of dem electric superchargers that I seen on those TV infomercials?

Is the tornado whatchamacallit one of dem whirlygig thingamabobs?

You forgot to mention that you put in that six speed with 4 overdrives.

biglg

Shark, you hit all the nails on their heads. THe tornado is the best. I think it helped MPG by about 4, just as advertised.

tj

Is this true? Doesn't the fuel injection meter/monitor the amount of fuel delivered to the rail? If so, the DIC is an accurate computation since it knows how much fuel consumed and how many miles traveled.

73shark

What you say is accurate I think. I don't actually know how Chevy does it, maybe ZX could elaborate sometime. I do know that on both my TrailBlazer and now Tahoes, that the DIC tends to run about 0.5-1.0 mpg better that actually. I realize that a fillup is exact either, but I always stop at the first shutoff and the trend is that actual is a little less than the DIC. I think it's just like all measuring devices, there's a tolerance associated withit. And it costs money to reduce that tolerance.

ZX1100F1

The MPG average displayed on the DIC is not usually 100% accurate.
While the computer does use fuel quantity and pressure supplied to the rail; you need to keep in mind that the system is open ended and much of that fuel is not consumed and is returned back to the tank un-metered so the best that can be done is a rough educated guess so to speak. Another reading (parameter) that is used is fuel injector duration.
There have been a couple of software updates aimed at making the DIC display a more accurate average economy and for those of you with the update your DIC is going to be more accurate than those without it. Most of you will find that the closer you are to reading an average of near 18MPG the more accurate the cross-check will be and the further you get away from this average (either + or -) the less accurate the reading will be.

jeffshelton12

Just adding my 2 cents here. I drove about 10,000 miles on the stock 17's about 90% highway and was getting around 18 mpg on the DIC. I just upgraded to stock 20's and had the computer flashed about 2,000 miles ago and my mpg has of course gone down to around 16.5 mpg on the DIC. I have no engine modifications.
Everyone is correctabout the V8/V4 switching. It will never stay in V4 mode unless you hit the breaks or are going downhill. I love driving in cruise control b/c I'm always highway driving and was a little disappointed at first when it didn't go into V4 mode on level surfaces but thats the price you pay forhaving an SUV. I'm still Loving my Tahoe even though the gas prices just went up again. I can't complain too mush about that b/c I work in the Oil/Gas Business.

ZX1100F1

I've got mine to stay in V4 mode for the full 10 minute cycle plenty of times, but you guys (along with GM marketing and some dealership salespeople) are making way to much about the perceived fuel saving benefit of being in V4 mode.

Remember that: A heavily loaded 4-cylinder engine is less efficient than a lightly loaded V8.