Chevrolet Tahoe Hybrid vs. Mercedez-Benz Gl320 CDI

[PA Dweller]

I would rather have the Tahoe, gasoline is cheaper. Now when will GM bring the 2 Mode Lambda's? I bet a 2 Mode/DI Buick Enclave would own this MB.

[BlueMontreal]

The Tahoe has lower emissions and diesel is more expensive than gasoline.

[tgagneguam]

Overall, this seems to be a fair review, 91fairladyZ. No matter the Benz's triumph, I still find it refreshing that several of GM's vehicles lately have been able to stand a comparison with good foreign competition. Who woulda thunk that you could compare a Benz to a Chevrolet and not laugh in hysterics?

We guess that makes Paris Hilton, proud owner of a 2008 GMC Yukon Hybrid, the hybrid Tahoe's twin, a forward-thinking early adopter at the vanguard of the green car movement.

I'm quite happy to say that I did not know this is how Ms. Hilton travels. If I were GMC, I would never, ever advertise her choice. Ever.

[tgagneguam]

Originally Posted by BlueMontreal

The Tahoe has lower emissions and diesel is more expensive than gasoline.

I, too, shared one of your concerns, BlueMontreal, though the article addressed it near the closing:

...The diesel GL also handles and stops better, while offering superior seat comfort and utility. And with its combined fuel-economy average of 23.9 mpg offering a substantial margin over the Tahoe's 20.9 mpg, the Benz easily wins our fuel-economy test, too.

Of course a comparison of fuel prices equalizes the game a little. During this test, we pay $3.579 per gallon for the Chevy's 87-octane gas, while the Benz's diesel costs us $4.179 per gallon. But because of the GL320's lower fuel consumption, we actually spent only a dollar more overall to fill its tank at the end of our test...

[ForcedTQ]

Originally Posted by Michael_S

The normal GM Vortec 6.0 liter that is very well used is a non-variable valve timing V8 running the Otto combustion cycle (same valve time on intake and exhaust valves) with a 4-speed hydramatic automatic, and its reliability is proven.

The Tahoe 2-mode 6.0 liter V8 has variable valve timing, uses the Atkinson combustion cycle (shorter valve time on intake than exhaust, and this is the first engine GM has made with that technology that I know of), and has a new electrical system and very special transmission that combines aspects of a continually variable transmissions (CVT) with a traditional 4 speed automatic.

I am going to have to correct you on your incorrect description of the Atkinson cycle. The Atkinson cycle actually utilizes a longer intake valve event that lasts longer into the compression stroke, (thats the stroke right after the intake stroke). This allows the piston to rise in its bore with less restriction than it would have otherwise.

A side effect of this when used in a naturally aspirated configuration, is reduced Maximum engine power caused by reduced volume of Oxygen present in the combustion chamber during ignition; that occurs because some of the intake charge was expelled back through the open intake valve during the compression stroke. This is why the Horsepower rating of this engine is some 45 HP less than that of the same engine using a conventional intake lobe timing camshaft. The benefit of this cycle is increased engine efficiency caused by reduced pumping losses, hence why they chose this cycle for the Hybrid application.

The rest of the engine it self is using the same components as a traditional L76 6.0L engine that comes in the entire truck lineup. The only component that has changed is the camshaft. The L76 has an adjustable camshaft phaser, that either advances or retards the camshaft lobes I and E equally.

[rmodys]

Why do they have to have those awful decals on the side of the Tahoe? If it was 1985 it'd be forgivable but my God...

[BlueMontreal]

Originally Posted by tgagneguam

I, too, shared one of your concerns, BlueMontreal, though the article addressed it near the closing:

GL320 is 14 K pricier comparably equipped and even if it has better fuel economy, with diesel being pricier, it would take many years to even the difference.

[member12]

THe benz looks like a functional SUV, the Tahoe Hybrid doesn't.

I like the Benz.

[American_Muscle]

thats a ridiculous price for the tahoe hybrid

[ddl]

I think the same sentiment was echoed by Car and Driver in their test of the Tahoe Hybrid - good improvement in fuel economy relative to the gas version but still not as good as a diesel so why bother at the same price?

I believe the M-B GL diesel was once again the comparison vehicle.

At least GM will have their bases covered with the Tahoe hybrid and the Tahoe 4.5L diesel plus the gasoline engines as far as large SUVs go.

DDL

[PA Dweller]

Originally Posted by ddl

At least GM will have their bases covered with the Tahoe hybrid and the Tahoe 4.5L diesel plus the gasoline engines as far as large SUVs go.

When is the Tahoe supposed to get a Diesel? Price?

[stevecmh]

not bad.. i am surprised there is not more of a price diff.. the MB looks pretty good

[Michael_S]

Originally Posted by ForcedTQ

I am going to have to correct you on your incorrect description of the Atkinson cycle. The Atkinson cycle actually utilizes a longer intake valve event that lasts longer into the compression stroke, (thats the stroke right after the intake stroke). This allows the piston to rise in its bore with less restriction than it would have otherwise.

You're right, you're right. I had it backwards.

A side effect of this when used in a naturally aspirated configuration, is reduced Maximum engine power caused by reduced volume of Oxygen present in the combustion chamber during ignition; that occurs because some of the intake charge was expelled back through the open intake valve during the compression stroke. This is why the Horsepower rating of this engine is some 45 HP less than that of the same engine using a conventional intake lobe timing camshaft. The benefit of this cycle is increased engine efficiency caused by reduced pumping losses, hence why they chose this cycle for the Hybrid application.

The rest of the engine it self is using the same components as a traditional L76 6.0L engine that comes in the entire truck lineup. The only component that has changed is the camshaft. The L76 has an adjustable camshaft phaser, that either advances or retards the camshaft lobes I and E equally.

I see.

Also, in addition to the reduced pumping losses, I understand the other advantage of Atkinson is that the fuel expands to a greater volume than it is compressed. Since the intake valve stays open long enough for some of the air to be pushed back out of the cylinder before compression starts, the air might only be compressed 8 times but then expand 10 times on the combustion. That extracts more power than when the compression and expansion ratios are equal.

...if I understand it correctly.

[goblue]

The proper competitor to this is the coming 2 mode Enclave. GM's solid rear axle hurts - and is to very little benefit in this vehicle. Off roading in a hybrid with all those low air dams? Nope. Big time towing? Nope.

Cadillac needs to move the Slade to a unibody IRS - not lambda necessarily, but something similar. If you want to keep the Tahoe / Suburban line setup to work, fine. Then use diesel. However, its not the right vehicle for a hybrid system. Lambda is much better setup for it.

[PA Dweller]

Originally Posted by goblue

The proper competitor to this is the coming 2 mode Enclave.

Please tell me you have details.