Spotify stops in my car

[isinyc]

I've always had to 'trick' spotify into playing my car.  When I connect the phone via the USB connector (iPhone5) and played spotify it would stop after about 30 seconds.  So I had to trick it....i would play iTunes and in the middle of the itunes song go into spotify and start my playlist...(I could then only change songs from my phone not from my cars stereo buttons).  This was ok as i got to have my music however after a recent upgrade to my iPhone this no longer works either.  I simply cannot play sptofiy in my car stereo..