Vehicles and reality:
Like the Harley Davidson HOG style macho motorcycle and the bicycle. Also like the pre A17 mini-bike. So don't take what is below wrong, please. I am hoping for some realistic considerations by the pimps.
In a realistic apocalypse...roads would degrade quite fast. While there is some hazards(cinder blocks, etc) placed on the roads in 7dtd, realistic the roads would be much worse because pavement buckles, cracks, holes develop over time mainly due to temperature changes. In addition, vegetation would start growing in the cracks. Vegetation growing in pavement also will break up the pavement over time.
In addition, most travel would be off road.
Because of the above reasons, a pavement only style Harley Davidson HOG style motorcycle, a passenger car and even the A16 minibike would not be very useful in a real apocalypse except maybe the first year. These types would get stuck off road and would have great difficulty in handling the rough terrain that would occur after a few years of non-maintened roads in apocalypse.
4x4, and AWD vehicles with aggressive/knobby tires and good springy suspension is what a real human would gravitate towards if available.
My suggestion is at least change the art/skin of the mini-bike and big-bike to include more aggressive knobby tires and at least hinting at some quality suspension where the wheel moves up/down in relation to the frame by showing some springs. Would prefer the physics of the vehicles actually incorporate the suspension and traction concerns mentioned, but understand that is difficult to code. So at least address this issues with art changes.
While the existing mini-bike does have aggressive tread + wide tires appropriate for rough terrain, the mini-bike has zero suspension and any high speeds over rough terrain would render the mini-bike extremely difficult to drive if not out right crash due to rough terrain.
The HOG is even worse, low clearance, looks like all-season tires and again no hints of suspension.
In A16/A15, the mini-bike is too fast(Speed). That looks like a 1HP lawnmower FFS. That would be like 35mph on a downhill slope and struggle up steep terrain.
Lastly, in a real apocalypse I think humans would gravitate towards anything 4x4,AWD truck/suv types, ATV's and quad style side by sides.
I own 2 ATV's with 2up seats, 2 4x4 trucks and an AWD luxury car. I regularly take my family and go off road deep into the rocky mountains mostly on the ATV's cause they are by far the best in rough terrain. I know from real experience the need for 4x4 or AWD, aggressive low-air pressure tires, ground clearance and springy independent wheel suspension when going off road in rough terrain.