Friday, June 30, 2017

Discoveries in the Jaguar XF

Jaguar's adaptive cruise control has two features from what I have read:

1. Brakes when you get too close to another car.

2. Slows you down to the set cruise control speed if you are going down a slope and engine braking isn't doing the job.

The first feature is a substitute for an attentive driver.  If you need this, put down the cell phone or the electric shaver and drive.

The second feature is actually useful.  I have nothing but significant down grades from my mountaintop Shangri-La to... pretty much anywhere.

If you don't have adaptive cruise control, I have discovered a so-so substitute for feature 2.  Press the race flag button and the dynamic stability control button (the car has snakes under the wheels).  You may have to hold for a second or two.  I am not sure that both are needed, but that's the combo that I have been experimenting with.  Now put the transmission in S (semiautomatic mode).  Set the cruise control on your downward slope.  Except on very severe and long slopes, it holds the requested speed.

How?  The Trac DSC mode (I think stands for Track DSC) biases the transmission into a lower gear.  This makes it fly like a bat out of hell when putting the hammer down.  It also keeps it one gear higher than normal, reducing speed when rolling down hill, so cruise control can keep the desired speed.

This is not completely effective on very steep grades, because it wasn't designed for this.  If you going down U,S. 395 south just north of Mono Lake, you better plan on using the - paddle shifter at times.

This use of Trac DSC to bias down the gears should reduce gas mileage, but it seems to be subtle if at all for me.

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