Also, apart from my other thread, when driving some distance on cruise control, it suddenly turns off while I'm relaxing in the chair, not touching the brakes, not shifting gears.

This is an Automatic 1.5L Sports, didn't touch paddle shifters. Ideas?

 

Using the paddles with cruise on doesn't deactivate it at all.

Have you checked the brake pedal switch to ensure that it isn't intermittently failing and deactivating cruise?

Have you tested the switch itself for continuity in each button position?

You might have an intermittent break there OR possibly a brake pedal switch that may be in the early stages of failing. The brake pedal switch is the easier of the two to check since you'll likely have to remove the airbag and possibly the steering wheel in order to get access the connector.

 

It happened to me couple of time in the 9 years since I own the car. Maybe 10 time total.

I do a lot of city driving and I use the cruise on long stretch of city street. around 50-55 KPH. and it does not happen often ( and don't remember it happening in the last 2 years), but yeah, the cruise control turn off on it's own and not only that, it also forgot the speed you had set. Pressing "resume" doesn't work.
But it seems to me happening to me on the same street. So I wonder maybe bumps ( which were plenty on that street) and bad condition might increase the load on the engine. Maybe there's a security in there, when it feel too much load it just turn off. I never read anything about that, it's just a hypothesis I had. Because it's something that happen tome like randomly maybe 10 times on the course of 7 years. So it's not a regular issue.

My fit is a 2007 sport manual with 114 500 km ( around 71 500 miles)

 

I would guess that there's a loose connection or failing switch in the steering wheel controls. I've heard of the main cruise power switch wearing out for one or two people; if it jostles to the off mode momentarily, it would cause the symptoms you describe.

The cruise should not unset itself just from moderate bumpiness. If the VSA/ESC system kicks in (if you have that on your car; I don't know when exactly it was introduced), that may force it to disengage. I don't think even then it would lose track of the set speed.

It wouldn't seem to me to be a problem with the brake pedal switch since that would not make the cruise control forget the set speed and not be able to resume.