42037 4x4 RC Mod
It has double wishbone suspension, 4WD with 3 differentials (front, central, rear), 2 L-motors for drive, 1 servo motor for steering and BuWizz 2.0 for controls and as a battery. Steering wheel in the cabin is connected to the servo, so it rotates when the car turns.
I wish it had locking differentials, but that's probably too much for such a small (?) Lego car. An engine block would have been nice also, but in my experience the servo motor has to be as close to the steering rack as possible to reduce the backlash, so I chose to put the servo motor in the front of the car. The model file uses 6.5 hard springs, but they are probably too hard, judging by my 42037 original set, so I'm planning to build it with soft springs to test.
BuWizz 2.0 is represented in the instructions by a block of dark bluish gray bricks in the back of the car. Standard Lego batteries won't fit there without a remodel of the rear part.
UPD 2018/06/25 As mentioned in comments, BuWizz dimensions were wrong (I trusted the official site, that they are 3*4*8, but they are actually 4*4*8 studs). I fixed the problem now.
UPD2 2018/07/05: Finished the build IRL, had a couple of problems with front and rear wheels trying to drive in opposite directions, had to rotate rear diff 180 degrees. BuWizz was very hard to access, so I placed it vertically, now it's easy to remove, and you can even charge it inside the model. The instructions file and parts list are updated.
UPD3 2018/07/19 : Found out, that the steering wheel rotates in the wrong direction. Fixed the instruction and updated the parts list.
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These types of files are created with the LDraw system of software. You will need to install compatible software to open and view the instructions. A full list of available software is on the LDraw site.
This MOC also has a 3D digital file available (eg LDD, MPD, etc): 3D Model