TV550

Hello everyone, Ive been a lurker of these forums for a year and will either get the GL 320 or GL 550 but have not made up my mind yet. I just dont seem to understand the function of torque vs horsepower.

I have read on the net the definition but still dont understand it in layman's terms.

Torque = force to turn a wheel which gives you quicker response but why doesn't equal faster speed?

HP= power to turn the wheels faster but does not give you the feeling of quicker response, so higher horspower and low torque can still leave you wanting more from start?

So why is the GL 320 1 second slower than the GL 450 and GL 550 0-60mph

Thanks for any help or did I get it right?

GL Troll

In practical terms, higher HP tends to give you better response at higher speeds – say above 70 MPH. And you are right, high torque launchs you harder from a dead stop. Then there’s the excellent Honda S2000’s low torque/high HP. Don’t ask me to explain that one.

You’ve probably heard of torque curves. The flatter the better. Which means the peak HP and torque numbers don’t tell the whole story. This seems to be where the GL 450 has an advantage as the peak numbers seem fairly modest for the performance you get. The 550 must be incredible. It’s also helped by a great 7 speed transmission.

AsianML

Low curb weight? Probably much more to do with gearing.

scottybdiving

Torque is a static force. HP is when distance and time (RPM) are calculated with torque. This is why gas engines always have higher HP even with less torque than a diesel. Their HP is calculated at a much higher RPM.

nygl320cdi

The torque is the pulling power of the engine, its the twist the engine develops to get you going from a stop. I recently had the same choice, I drove the GL 550 and 320. The 550 was FAST and had some nice options that you cant get on the 320. The 320 wasn't as fast off the line but its no slouch either, its able to keep up with anything land rover, toyota/lexus or GM have. (where as the 550 will probably surpass them) In the end the 320's price and fuel economy was more enticing so I ordered one.

BlownV8

HP = torque X RPM / 5252

Hp is just a calculation of torque at a specific RPM. The GL320 is more than 1 second slower to 60. From the actual tests I've seen, the GL450 is in the 6.4 to 7 second range while the Gl320 is in the 9 to 9+ second range to 60. However, the 320 wins hands down in fuel economy, will have better resale value, and will be able to rack up more miles than the 450.

I noticed a huge difference in performance driving both back to back. The 320 is not quick compared to the 450 but the performance is adequate for an SUV and the economy, as mentioned previously, is much much better than the average SUV. I didn't think the 320 was necessarily slow compared to other SUV's but it was slow compared to my old Renntech CL and is sluggish compared to the 450.

In town you will hardly notice a difference. However, when you are trying to quickly merge with traffic or if you are driving quickly with frequent quick WOT bursts, you will notice a big difference. These vehicles are not speed demons by any sense of the imagination and should not really be judged how quick one is compared to the other. Chose the vehicle that is right for you and your family.

The 450 and 550 will be easier to live with since unleaded is far more common than ultra low sulfur diesel. You don't have to search for super unleaded but you will have to search for the ULSD. Given the 320 gets significantly better mileage, you won't be filling up as frequenlty as the 450 or 550. The comparison is not cut and dry so choosing one may be difficult.

I chose the 450 but it was more out of economics than performance. I found a 450 that was two months old, had 1,800 miles, close to $10,000 off MSRP, and came with a 100,000 mile warranty. The 320 was my first choice but the additional mileage per gallon, in my case, would never have made up for the difference in price between the new 320 and my ever so slightly used GL450.

StevethePilot

Short points; probably because of the lower-to-the-ground profile and stiffer suspension, I've convinced myself that the GL320 is faster than my LX470 was. Then again, the 470 was a heavier vehicle and did have 217,000 miles on it. (Anybody counting how many times I've said that?)

As for economy, I filled up before the Las Vegas meet in Scottsdale, drove to Vegas, drove to dinner, drove around Red Rock, and drove home to Scottsdale. Then I filled up again. My 470? I think I had to fill up twice on the way to the grocery store around the corner.

I've done enough highway driving to know that there is a difference, but oddly enough there always seems to be a bit more available when I push a bit harder on the pedal. I can imagine how much nicer the 450's acceleration at speed is, and I cannot imagine the 550's! But having more than enough oomph with that wonderful long-haul mileage is just a real blessing.

IMHO.

STP

lkchris

So why does it matter when you're getting so much better fuel economy?

The GL320CDI can definitely get out of its own way and can violate every speed limit in the country just as it is.

Torque? Drive over a mountain pass sometime and feel it pull. No sweat; doesn't even breathe hard.

BlownV8

The 7 speed tranny makes a big difference in acceleration compared to others 4 and 5 speed tranny's.

I was laughing out loud at your 470 comments. The hp and tq ratings on a 2005 LX470 are 235 hp and 320 lb-ft of tq with a 5 speed tranny. You had almost as much hp but it was available much sooner than the 470's. Your 320 probably is quicker considering you have a 7 speed vs the Lexus 5 speed tranny. The 2007 LX470 does not have much more hp/tq than the 2005 and still has a 5 speed tranny.

oknish

I wonder if TV550 is still drinking from this firehose

http://www.revsearch.com/dynamometer...orsepower.html

LEOSOPHIE

The 550 has 75% of it's torque available at 1000 rpm's and over a broad rpm range. This available torque is similar to available torque in a diesel.

Stumblefoot

TV550,

In the end, you'll be happy with either vehicle you choose. It really just boils down to personal preferences (fuel mileage, options, etc.) when deciding between the two vehicles.

I can tell you that our GL550 constantly astounds me. When I'm climbing the 7% grade on I-70 to our house for 5 miles, I only pull 2100 RPM's at 75mph. My Trailblazer on that same stretch of road typically roared at 4500 RPM's. The power on the 550 just seems to be endless.

Good luck in making your choice!

TV550

Its nice to hear other people share their thoughts on the matter. It really is a tough decision between all three GL engines they are all so good. I am mainly concerned about merging speeds on ramps and such but it looks like the GL 320 is able to do it no problems, since no one here has ever complained that the 320 is sluggish while merging.

Another good thing about the 320 engine is I think you save 30.00 per gas tank over the 450 or 550 engines that comes out to about 120.00 per month savings on fill ups.

By the way does the 320, 450 and 550 all share the same air suspension? I looked at the online info and could not find that info. If the 450 and 550 have sportier suspensions that might sway me.

Why dont they just release the GL 420 CDI to the US and that would be it.

Thanks again for answering

Nevada Jack

The 320 and 450 (without the ORP) do not have ADSII nor is it available as a separate option. It is standard on the 550. With Sport Mode selected in the 550 it handles like a sport car (well almost) and the ride is quite firm but sure footed. In Comfort Mode it is quite soft but on bumpy roads makes the ride like a large sedan. Standard Mode is a combination of the two. If mileage is your main concern then the 320 is probably a better selection. If performance is your thing, then the 550 may be the best. The 450, like the Standard Mode is a combo of the two...:-)

nantucketsleigh

If you value handling, ADSII is a must IMO. I thought it was standard on the 450 and was disappointed when I learned it was not. My wife couldn't care less and loves the 450 as is.

Fifth Ring

If it was a performance sedan, the lower HP number might be disappointing at times. But for an SUV used primarily in town (0-45mph) or for family long-hauls, the absence of HP is much less of a concern. It's really torque that matters in town.

I also look at the engine selection with a longer view. As of today, there are very few diesels offered of any kind. But by 2009, there will be a bunch of them; and they will start to supplant hybrids as the new "efficient" SUV engine. So, I foresee diesel becoming a strong resale preference in the longer term.

StevethePilot

You make a good point, and my 470 was a 1999, so ... I guess it probably is faster! Not just my imagination after all ... huh.

STP

TV550

Jack,

So ADSII is only an option for the 450 and standard in the 550?

All the styles have air suspension correct? The MB website is not to clear on all this. I did not see the option for ADSII when I did a build it yourself on the website for the 450.

What is ORP?

Thanks

Quicks

Only available on the GL 450
From MBUSA Site: Build Your Own GL 450

334 Enhanced Off Road Package details $2,250
· Center and Rear Locking Differentials
· 2-speed transfer case
· Skid plates with underride protection
· Dynamic Compass Display
2008 Packages
334 Enhanced Off Road Package

The GL-Class may be refined, but with an Adaptive Damping System (ADS), two locking differentials, skid plates with underride protection, and roof rail crossbars it proves it's not afraid to get dirty.

GL Troll

ORP = Off Road Package

GL Troll

That brings up another good point(s). Thanks for waking me up. Weight is an equal partner with torque and HP. Weight to HP and Weight to torque ratios are more relevant than any of these by themselves especially at low speeds. Traction and wind resistance are also important.

The coefficient of drag, Cd is also a popular number. But the actual air drag is proportional to Cd times frontal area, the frontal area being equally important as weight is with power. Air drag, of course, comes into play at higher speeds.

So, in the end, it’s probably best to compare 0-60 and ¼ mile times. If one vehicle seems to do better in comparison on the ¼ mile, it’s an indication that it may pull more strongly at higher speeds. It may also just have a traction problem initially. These numbers do tend to overstate the importance of a good initial launch. Since I’m older and more mature now (sort of….a little.…ah, who am I trying to kid?), I tend to value acceleration at higher speeds more than from a stoplight. Sometimes you see passing-time acceleration runs i.e. 50-70 MPH or something. These can be helpful but I’m a little suspicious of them. My theory is a vehicle can get lucky or unlucky because of gearing and where the shift point may be in a particular speed range. Maybe they should widen the range. Do 50 to 90 MPH runs.

oinick

Look, I had a 2006 LX470 that I traded for the GL 320. The Lexus is way more luxurious but not nearly as user friendly, especially considering car pooling and those sh**ty fold up rear seats. This doesn't even take the horrendous MPG of the Lexus into the equation.

I really regret ever getting the Lexus. It was a very expensive mistake. I wanted to try the Lexus because I had never had one.

The GL is superior as a driving car. I love the diesel MPG and the way it drives. The Lexus was more comfortable on a long trip in the way the seats felt, and the nav was better. But considering the fold down rear seats and the diesel engine, I am glad to have traded up to the Mercedes.

Danno4x4

Here is a little analogy that I like to use when talking about horsepower and torque...

Think of how you versus your 14 year old son might crank down the tongue jack on a boat trailer with the weight on it...

He has a bit of trouble getting it started but once he does, man he cranks that sucker fast... And uses up a lot of energy doing it... You might say he has lots of horsepower.

You on the other hand have no trouble getting the jack started... You crank away without much effort, at a nice steady pace... You are capable of cranking nearly as fast, but you take it easy cranking at a semi brisk pace. Not as fast as your son... You have lots of torque.

In the end, you son can crank the trailer up faster than you can. He does more work in a shorter amount of time. But, he is pooped when he is done, since, he used a lot of energy to do it. You can't crank the trailer up as fast, but it is really not hard work for you... You can't do the work in as short of time as your son. But you didn't really expend much energy doing it.

Torque, by the way should really be the most important between the two when discussing larger SUV type vehicles. For Little lightweight race cars like my Subaru STi, horsepower is more important.

sraj

I have come to use Sport Mode for all but the roughest road surfaces. I like how the body motions are damped and how flat the truck handles curves. I find that in Comfort and Standard modes, there is too much pitching and bobbing. In fact, I haven't been able to tell the difference between Comfort and Standard. I'm just glad that I have ADSII, because in the non-sport modes I find the ride to be a bit unsettling. Then again, this is the first truck/SUV I've owned (I've been driving BMW 5-series for the past 10+ years) so maybe I'm still in the adjustment period.

By the way, the other day I was performing a passing maneuver on the highway. I manually downshifted 2 gears and hit the gas. The 550 simply blasted forward (quicker than my 540i/6, I'm pretty sure). At that moment I did not care about fuel economy or even social responsibility.

StevethePilot

What's going on with your son and his crank? Gee whiz, that's a bit personal!

BTW, was that you I caught at Chic-fil-A the other day?

STP