Seat belts are worn as a safety precaution, toprotect the occupants in case of an accident. Many countries have now made this law
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Check the wires that you cut, they may be touching each other or shorting to ground.
to attract other drivers attention
Whilst both vehicles are parked.
The rules around this issue vary depending on where in the world you are however in the UK the DSA say that your vehicle must pass MOT in which the condition of mirrors and other safety equipment is required.
Sure, as long as you have your drivers assigned to the vehicles they drive then they can drive any other vehicles in the house.
Yes special insurance is required for all "working" vehicles, that is vehicles that do heavy work. Garbage trucks and other Tipper vehicles require insurance that reflects the heavy work they do.
recommended but not required by law.
Not sure what veihcle is. The distance between two vehicles depends on their speeds, the conditions of the vehicles, the road, the drivers' alertness and many other factors.
Many vehicles have a production date listed on a sticker with other information in the drivers door jam area.
Unless your seatbelt is on. aswell as other passengers, the seatbelt light will not turn off. It is a safety precaution and I highly doubt you can disarm it.
Only your insurance company can answer that - mine does... I have insured vehicles that were not in my name and insured vehicles in my name for other drivers - Geico... I have also loaned vehicles that were in collisions and they still covered them even though I did not specifically "add a driver".