I have a lovely, quite low mileage BMW 740i. Sometimes - unpredictably - it won't start on the first, second... even 13th or more turn of the key. It can be the first start of the day or after I have run the car a while - there is no pattern.

I hear a faint click when I turn the key, and have to do it again,, and again. It always starts eventually. It has nothing to do with the charge in the battery, or whether I am pressing the brake or whatever. I have tried wiggling the gear selector thinking that the park sensor might be faulty but this doesn't help.

For example, it gave no trouble for several weeks, and started first time today after being left for four weeks unused. I drove it for 20 minutes and stopped and it started again first time. I stopped again and half an hour later it wouldn't start. It did after about seven turns of the key, as vigorous as ever.

I drove it some more and stopped... and again I had to turn the key about 10 times to get it to start. My local garage thinks the starter motor is at fault but as I say, when it starts, it starts as vigorously as ever. Have you encountered this before?