I have meant to get to the bottom of this for years and hoping somebody has an answer. Ever since our 2013 was under warranty, hard acceleration, full floor flat, such as joining the highway, seems to fill the the cabin with fumes. It usually takes 20 or so seconds after the event for the smell to be become apparent. I then usually open the rear quarter windows and open a drivers front a little to let flow through air flush it out. I had the van inspected under warranty and the dealer said they couldn't duplicate. I very, very rarely floor the vehicle anyway, so I kind of let it go, albeit foolishly maybe. I could never work out if the fumes were exhaust or spent oil, but they sure irritate my nose. The good news is though, my sense of smell has deteriorated over the last few years. We've only done 50k miles in the 6 years we've owned the van. Anyone?