I'm going for the full hover conversion. I plan to copy the folding wheel mechanism from the 1/18 Sunstar DeLorean, but make it tighter and stronger, so it doesn't rattle around as much. I'm going to install micro servos for each wheel, so avoiding having to build a mechanical linkage that joins them all together. Lights on each wheel, the exhausts and flashing lights on the underside will come on automatically, when the wheels are down.
Also plan to add extra wiring bundles to the interior, build the Mr Fusion from scratch, add LEDs to the dash binnacle, time circuits, plutonium gauges and the 3 marker lights on each door. I also want to rewire the headlights, so i can have just 2 or all 4 on at a time.
A big job will be to drop the floorpan in the centre of the car. HT added all the hover conversion stuff to the underside, but kept the height of the floor the same as the standard car, thus reducing the interior space. That's why Doc doesn't fit in the car. I want to add about 1/2 inch extra height. At the same time, i'll add carpeting, push the seats further back and change the angle of the backrests. The seats are all wrong to try and compensate for the reduced height. Any figures put inside are lying down, not sitting up, so their necks are at the wrong angle, making them look odd. Also add pedals, handbrake lever, sunvisors and make the steering wheel tilt, so it's easier to get figures in and out.
I think that about covers it. Even if HT brought out a 2nd version, it will still have most of the faults listed above, so i'm not bothered now if they release it or not. Despite all that and the huge amount of work involved to upgrade it, it's still a very nice piece to have in one's collection.