I'm thinking of buying a 08 Yukon hybrid and the dealer let me take it overnight. I put $20 in the tank and drove about 60/40 hwy vs city driving. I reset the trip computer when leaving the dealer and at the end of my trip the ave MPG was showing 16 MPG ??? It came up from 15 MPG on the 10 mile HWY trip back to the dealer. Is this normal ?

 

Pretty much.

There is a way to drive these vehicles to maximize fuel efficiency, making maximum use of the electric and 4cyl modes ... otherwise, 16mpg sounds about right and what I averaged over a year on 75/25% city/hwy driving.

At the end of the day it's still a huge brick with a 6.0L under the hood and I never got anywhere near the posted mpg ratings, but then again neither did that lady who sued Honda.

Still anywhere between 4-8mpg better than the 5.3 Tahoe/Yukon and the 6.2 denali/Escalade ... trust me I know.

 

So I'm wondering HyHoe and jfreeman do your front wheels need frequent cleaning of the brake dust from the front pads? If so that is definite proof that in "routine" braking you are exceeding the electric Re-Generative power limits. Hard normal stops. Nothing wrong with that just brake pad replacement sooner and hot rotors instead of a charged up HV battery. If you are the first one to the next red light, and that 6 liter will do it, then you are exceeding the electric boost power limits.

So driving style is a leading factor. Now for me, I accelerate hard enough to always stat the engine. I have driven most of the hybrids out there, and nobody has one that won't upset the guy behind you if I try to accelerate on all electric.

I can routinely get the sticker fuel economy in summer. But I drive like an old man.

 

When I test drove the 08 overnight I tried to be easy on it in the city driving to see how far it would go on ele only. It would never get above 5-8 mph before the gas kicked in. Is this normal ? I drove a 2nd one at Carmax yesterday and it did the same thing. It would not stay in ele only just rolling though the parking lot at jogging speed. Both of these 08's have around 45k miles.

 

It is all in your pedal. The vehicle will go as fast as 28 mph on electric. It just takes a real long time to get there. It is all about the power required at any time to accelerate. The HV battery will allow about 30 to 33 killowatts of electrical power to be taken from it at any time. So 42 to 44 horsepower. A 6200 to 6500 pound SUV does not accelerate very fast on that alone. Then some of that power is taken by vehicle electrical loads and AC. ~ 3 HP usually.

Next if you understand Calc 1, is the derivative or how fast you push the pedal. If you increase the accelerator pedal faster than a programmed rate, the system will start the engine to be able to handle the giddy up you might want.

From a stop in electric, increase pedal slowly to about 5 to 10 %. If you can hold that steady and have enough room like the back lot at a big mall, you can allow the system to gradually achieve the 28 mph.

Now from the same stop in electric, quick blip the pedal to about 25% and abruptly let off to zero. In less than a second. The engine will come right on straight away.

It does take practice and most others are full hybrids are similar. Prius, 450h, Infinity "M", VW Toureg, all can accelerate in electric. Just NOT fast enough for the soccer mom in the mini van behind you.

The 2 Modes have an "EFF" gage. When the needle is straight up or a little left or right but in solid green, you are making the most of what the electric hybrid system has to offer.

If you brake hard or accelerate hard, the needle moves out of the green. It is not necessary to seek high amounts of drive cycle in electric. If you had a flat road and pedal real light, you could go about 3/4 mile in pure electric. (just over jogging speed ) My best in grid-lock metro Detroit traffic was 7/8 mile electric. I had AC off and everything I could turn off, off.

Most of that was let foot off brake and roll 50 feet at a time and STOP! However it was 20 minutes of NOT idling and burning any gas. Got caught in a Car-B-Que back up once on I-75 coming home on weekend. Several vehicles ran out of gas in that.

15 minutes engine off, 3 minutes on, repeat for the next hour and a half.

 

^^^ This is all of course correct ...

However other than to understand how these things work (which I personally enjoy), such knowledge isn't paramount to maximize fuel efficiency. Truth of the matter is that after a few weeks all of this is learned intuitively as one drives the vehicle and observes how it responds to the pedals.

There are folks out there who truly obsess with hybrids, staring at the hybrid drive nav display, trying to squeeze every last drop of fuel. I did that for about two days and realized that for me, it defeated the purpose.

It's a vehicle, and I wanted to drive it as I would any other vehicle. And driving it like any other vehicle I averaged about 5mpg better than the 5.3 versions of these trucks and about 7-8mpg better than the 6.2s. If I wanted fantastic fuel efficiency I would have bought something appropriate to that end.

These hybrids are fuel efficient relative to any other full size SUV, GM or otherwise ... but they are not by any means fuel efficient.

 

So my search is to upgrade from my 08 Sierra crew cab 5.3 that averages 13-17 MPG in real world driving. It sounds like the Yukon hybrid will match that. So Im guessing the non hybrid Yukon gets much less MPG that the pickup

 

That's about right ... at 50/50 city/hwy driving you'll be tween 16-18mpg depending on your driving style.

In comparison my 6.2 Denali averages 10mpg in the city ... I just took a long road trip from DC to Jacksonville and back and averaged 17mpg on a whole highway tank. If you did that in the Hybrid you'd average about 22.

The 5.3 SUVs are somewhere in between.

The major upside of the Hybrids is that they not only get greater fuel efficiency than the standard 5.3 Tahoe/Yukons, but that they also out-horsepower them whilst doing it.

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On a side note, i would caution you on purchasing an 08 model tho ... a LOT of 'first year' kinks seem to have been ironed out in the 09s and forward.

 

I don't know if it's all the heat we have had lately or maybe the summer blends of gas but lately I have only been able to get about 17.5 and I drive pretty conservatively. I used to be able to get just under 19. I do have 20's though with beefy cooper zeons.

 

MD80, look up the rolling radius on your tires and wheel combo. Your "stock" tire and wheel combo is set up for the computers and odometer to read a 0.391 to 0.395 (meter) radius accurately.

If your tires are taller, then the odometer and speedometer will under report actual miles driven. If they are shorter then your mpg is even worse.