If I could save just 5k miles a year over three years I would get the following savings. Fuel $4,250, one 20k mile maintenance on the 911, $2,500, 3 oil changes $750, Insurance $2k. Lets say just $2.500 more for the the rest of maintenance costs like brakes, tires, etc for an even $12,000. Thats a savings of $333 a month that after three eyars would leave me with a turbo with only 65k miles vs. 80k miles. And I am sure I could cut out more miles than just 5k a year on trips that didnt matter, mainly to clients. And it would actually be a lot easier to ask for rate increases with my clients rolling up in a mini vs. the damn 911.
So I am hard pressed not to think its a no brainer.
2015 - m4 - hopefully
2011 - 335is e92 - Cobb PTF E40/Rob Beck/AR/Helix (458 rwtq and 479 rwhp - @ 17 psi and 6,000 rpms)
2007 - 911 Turbo - EP1/AMS (617 awtq and 500 awhp) - Retired
2008 - 335i e92 - Cobb/AR/Helix/OSS (384 rwtq and 356 rwhp) - Retired
2003 and 2005 330i/ci zhp - Stock - Retired