NXP just sent me an email. They have a new automotive LED driver. ASL1002,4,7,10
I would look at LM3421,3,4,9 and LM3401,02,06 Down load LM3402. I can/have put this inside a bulb and no one will know.
I have two large trucks. I must have clearance light all around the top. If one bulb is out, any where, I can get a ticket. I am willing to pay extra for a long lasting bulb. Extra for a brighter bulb. Every 5 miles I burn a gallon of fuel. Four watts is nothing.