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Discussion Starter #1 (Edited)
Just curious, what sort of RPM's does your car sit at during a steady cruise at 60, 70 and 80 mph.

At 60, I'm at about 22-2300
At 70, I'm at about 25-2600
At 80, I'm at about 28-2900

Compared to what I came from, it seems pretty high, but it does well at those speeds. At 76-79 mph, the fuel economy guage tells me that it gets better mileage than it does at 70-73 mph. The deVille I had would sit at about 18-1900 rpm at 70mph, and at 80, she was spinning around 2300 rpm. Granted, she had a fairly large OHV V-8 and a very conservative 2.73:1 final drive ratio.


Chad R, '99 S320.
 

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75 MPH is about 2900 RPM for me, but I only have 4 gears.
 

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that doesnt matter because final ratio for the 4 speed is same as for the 5 speed ...meaning that in last gear they are both at same RPM (there is just one extra gear inbetween ..meaning 5 speed is bit smoother)
 

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In the GE my RPM at 80 is around 2500 or so and in my 500SEL its higher, around 3000 or so. I also get better gas mileage in my GE in both city and highway.
 

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that doesnt matter because final ratio for the 4 speed is same as for the 5 speed ...meaning that in last gear they are both at same RPM (there is just one extra gear inbetween ..meaning 5 speed is bit smoother)
Where'd they stick the extra gear in? I'd hope between 1st and 2nd, my car only downshifts to 1st below 27 MPH or so, 30 if I stick it in 2nd and hit the kickdown, the acceleration in 2nd is pretty slow because it goes all the way til 75 MPH for me.
 

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i have book on W140 i will read about the gearbox differences again but i just remember that final ratios were same.....but it might have been the older 5 speed and not the new electronicaly controled one
 

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that doesnt matter because final ratio for the 4 speed is same as for the 5 speed ...meaning that in last gear they are both at same RPM (there is just one extra gear inbetween ..meaning 5 speed is bit smoother)
I could be wrong, but I thought I remember reading the rated highway mileage shot up 3mpg between '95 and '96. How could this be true if the final ratios were the same?
 

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I could be wrong, but I thought I remember reading the rated highway mileage shot up 3mpg between '95 and '96. How could this be true if the final ratios were the same?
Could be wrong and in fact are. The 96 S500 highway mileage shot up 1 mpg - to 21 from 20 in 1995. I'm not sure about the top gear ratios or rear axle ratios but this could have been the result of the new ME engine management system.
 

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I was always under the impression that 4th gear was 1:1 and 5th gear was an overdrive.
 

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Hi Guys

on my 1998 CL 420, I could have swore that I was seeing around 1100-1200 RPM at 50mph... But last night on the way home that seemd to go up to arounf 1500RPM at 50MPH and 1800 RPM at 60 MPH. I not sure has something gone wrong or if I was just imagining the other readings... Do the higher RPM reading sound normal

I have 255/45/18 tyres on the car. I belive I have the 5 speed electronic box... and depenig waht you read on the net the 5 gear ration is 0.83:1... the final drive ration (Diff) in 2.82:1... I did read that the 500 was 2.65:1. I don't know if they are supposed to be the same on Both types of vehicles
 
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