i have Pilot and I have experianced the same. Especially when you have Patrol full tank and give a quick pickup.

The smell is close to Sulpher Diocside (rotten egg smell). What I heard was that the smell is caused by the michanism in the car to reduce CO (Carbon Monocside) discharge which converts CO in to a gas which is smelly. Keep your Air Circulation switch on while driving to reduce the smell coming in. But you can't stop it.