I'd go with the Kanger T3's - changeable coil and 3ml tank instead of the 1 ml tank in the M3's. Although the M3's look good for a cig style ecig. 510 auto batt or something ;- )
The T3's fix about 4 problems that people have had with the T2's - mouthpiece separating from the threading (T3 - mouthpiece is fixed since it's a bottom fill.) Dry hits - bottom coil on the T3 prevents this. Cracked tank (not common on the T2 but I had three go from checking to cracking/leaking) New fit for the T3 and now metal tanks on the 'MT'. And the three silicone 'rings' really makes for a tight seal - no leaks, no
juice in mouth.... You do have to eyeball the 'top' ring to keep it off the threads... but that's about it. You'll see the 'pressure system' when you refill, because you get some
ejuice from the coil area run out the mouthpiece (have a napkin underneath ;- ) And you can blow it out - not much - only what was in the coil area....
Anyway, it makes a no fuss clearo for the car and frankly anywhere else too and has the volume to boot.