Just my 2 cents. I've had after market warranty on both my 3 series and X5. I spent around $3000 per policy and it was money wasted. Here is what I tried to repair under warranty:

CV boot tore. I was not told by BMW dealer that there was a tear even thought warranty claimed the boot was probably ripped for 6+ months. This eventually led to damage in my front drive train and the entire front end needed to be replaced. Warranty company would not pay for repairs as failure was due to ripped CV boot. I went round and round with them that I never knew the boot was tore otherwise I would have repaired it. They didn't budge. They would pay for the CV repair but not the front drive system. I was out about $1.5k.

Next: I had water get into the rear of my X5 and short out my elecronic ride height module. Since the damage was caused by water the warranty would not pay for repairs. The water was there because I had damage to my rear in a collision which was repaired by factory dealer. Dealer claimed it was not their fault as they found sand in my rear hatch which caused the leak (faulty seals) even though they had to make an adjustment to the door which was slightly out of line. Either way, warranty wasn't going to cover it.

After market warranties cover very little of the actual items that have a tendency to fail once you start getting miles on your vehicle. I have an '03 X5 and I have spent about $4k on it over the last 3 months. Outside of those repairs that have been paid by me I have had no mechanical issues in the past 4 years since my warranty has expired.

Another issues: I have the pixels on my dashboard slowly going out. It's not that big of a deal to me but while it was at the shop I had them look into warranty replacing the dash. Warranty would replace it but only with "like kind" dashboard ie., a used one. I was told by factory service writer, don't know if true, that each dashboard is unique and that the only safe thing to do was replace with a new one - something to do with old one have certain codes? Warranty would only replace with used. If I replaced with new then warranty wouldn't cover any of the repair. I think they quoted me about $2500.

FYI - I cancelled my after market policies and received a refund based on current mileage and time remaining on warranty (about 50% of what I originally paid).

Check the fine print.