Hi all,

I hope I'm using the right terms here. My 1999 XKR had an MB 722.6 gear, and when I leave the pedal, seems to be stay at appropriate RPM for the speed, rather than going to idle.
When I switch to neutral while coasting it'll go to idle RPM and if I switch back to D, I can feel a kick.

Is this a normal behaviour? On other automatic cars I drive it was never like this.

Only had the car for 4 months, so don't know what to expect.

Thanks!

 

Foot off gas and surely RPM gently slow as the car gently slows? You have me worried now but I'm sure this is what every automatic I've had would do. Personally I would never go into N while moving, that just seems wrong. I believe there was an old Rover auto that basically disengaged drive on the over run but I don't think anyone felt it was a good thing.

 

Putting the gearbox in Neutral while driving (especially downhill) is called 'Mexican Overdrive' here in Texas.

https://en.wiktionary.org/wiki/Mexican_overdrive

 

It's not a common practice in the UK and I had a very worrying trip as a passenger with a business colleague who did it on each down gradient. He said it saved fuel but in his diesel the engine uses more idling (in neutral) than it does on the over run when essentially to fuel is shut off. Gave me the shivers.

 

Must be a second cousin of the Italian Tune-up.

Graham

 

 

Just so we're clear, I don't do 'Mexican Overdrive' regularly, or ever, was just trying this once as I wasn't sure about the behaviour of the transmission.
Either way, the RPM does go down with speed, just seems a little high to me, but maybe that's because my other car has a modern 8 gears transmission, so smoother and keeps the RPM lower when coasting.

Many thanks.

 

it has lockup in every gear

 

Try with and without SPORT MODE to see if the RPM is more noticeable in either?

There are TWO reverse speeds with the W5A580 gearbox so try it backwards?