The auto start/stop rarely, if ever, works. I've read a lot about how it should work and its subject to a lot of variables, however all being aligned, it still sometimes doesn't work. I've determined its likely that the battery isn't holding enough charge to do the stop/start properly, as if I do a 300 mile journey, it will work fine. Which also tells me the alternator is working (although how efficiently, I don't know).
The other thing is that sometimes the car doesn't start up easily. The starter motor will turn over quite slowly as if the battery is flat. Especially if it's been standing for a couple of days.
I've had the battery tested a few times all with different results:
- I've diagnosed it with Carly, and that says its fine.
- I bought a voltage meter (one that sticks in your cigarette lighter) and the voltage looks fine.
- One Halfords said that it was probably at 70-75% capacity/health and would likely need replacing soon.
- Another Halfords said the battery is good and that there's a "system noise issue" (what does that even mean?). He pointed at some switches to the side of the battery and said they might be causing the problem.