I bought a CPO 97 M3/2 and it has that 4yr/50k warranty and 6yr/100k "drivetrain". I have little idea what this second part is about and I don't have a good feeling that it covers much. I am planning to get an extended warranty for 6yrs (starting from that day I buy it)/100k (total odometer) for real warranty. I got a quote for $1850 (no deductible). Please advice if there are issues I am not seeing here. I also see an overlap of coverage. Is that even signifant? Please help!