Can I make a suggestion?
In no way undermining the OP's idea of an online petition, whilst it might generate a greater level of online interest a petition, will be remarkably easy for BMW to ignore.
If, however, you combine the signing of an electronic petition with a downloadable letter for people to add their name and address to it, spend a quid sending the letter recorded delivery, BMW will be forced to sit up and take notice when they have to employ someone full-time simply to sign for recorded delivery letters.
The petition can be used to give 'the cause' national interest (and use the web to increase its circulation) and use the letters to cause buggeration for BMW.
2,000 names on a piece of paper, especially online won't mean too much to them.
2,000 names on a piece of paper, along with 2,000 individual letters highlighting the same concern will be very difficult to ignore.
Gone but not forgotten:
325i M Sport (E92), Black Sapphire, Coral Red Dakota, 19" 225's, Seat Heating, 6FL and de-badge
Replaced by 6.2 litres of AMG powered C class.