I have used a DBV, a MFLB, WDZ, and an Invognito vape in the car. The DBV was nice because you could have someone else operate it and you could just draw from the tube and still have both hands free to drive, but the thing is so huge that it's a definite risk of arrest. As for the MFLB, I have used that with and without the PA and for in the car I much prefer it without the PA, the batteries are less cumbersome than the cables and you cna hit the MFLB with a batt stealthier than with the PA. The WDZ worked great, I especially like how you could plug it right into the lighter with no inverter, if you put it in a 16oz cup from McDonalds or wherever then it is pretty stealthy and small enough to easily hid if need be. But I would have to say that the Incognito vape is hands down my favorite for vaping in a car, it's super stealthy, has a light cable so it's less annoying, and looks like a friggin water bottle! Hits like a DBV but looks like a water bottle. The non attachable cable is a dead give away though if pulled over.
So they all have their pro's and con's, it's all up to what you consider the safest way for you to consume in a car. Oh and I only have an 80w continuous inverter and have been able to run all my vapes from it with no problems.