Revs too high

[Magyar]

Hi I have a mercedes 280 s e and when I drive 110 km/h the rpm is at 4000, this seems too high, why are the revs so high??

Thanks

[Max-NL]

Is it a manual transmission, or an automatic transmission?

[rumb]

MB has long designed engines that run all day at 4K rpm.  This increases fuel economy as well as stays in power range.  Compared to lazy american cars that run at 1500 rpm this seems odd to those not used to it.


PS put your  car in your signature and then it will always be visible to everyone.

[raueda1]

Hi I have a mercedes 280 s e and when I drive 110 km/h the revs are at 40000, this seems too high, why are the revs so high??

Thanks

Unless you have installed a turbine engine I'm guessing you meant 4000 rpm?  Gear ratios are HERE.  You can calculate rpm and speed.  Regardless, as an order of magnitude guess, it sounds like you're in 2nd gear.  Or maybe third.  You'd need to do the math to be exact. 

[Magyar]

Is it a manual transmission, or an automatic transmission?

it's an auto 1975 280se

[Randys01]

stuck in 3rd

[Magyar]

stuck in 3rd

I thought 1975 280se cars had a 3 speed gear box?

[Randys01]

I think you'll find it is a 4 speed box.

[Nabstud]

Sounds about right, remember that the tachometer isn't 100% accurate. Mine is similar, about 3600rpm. As said above, it was designed like that and will run all day at those revs. When you first drive it it definitely feels like its way too high but you soon get used to it.

The 4-speed box only uses first gear if you manually select it OR you put your foot down to the floor when taking off from standstill. In everyday driving it acts like a 3-speed auto.