Currently, you can tow a car by driving it fully onto a flatbed thing. I am suggesting a feature where the car that's getting towed is only partly lifted. So only the front (or rear) wheels are lifted, and the other two are still touching the ground and rolling. This can be an attachable feature for the D-Series, H-Series, and/or T-Series. Note that it needs some kind of turning/hinge point, so when the towtruck makes a turn, the lifted wheels of the towed car don't get all messed up. It can also just be a tow trailer/dolly: Sorry for my poor English. Citation / image disclaimer: https://www.metro.net/riding/fsp/ http://www.actioncameracars.com/td_sstdoll.html
