Engine
When you choose an engine for your kart, you have to consider what kind of ride you want from your machine. Gasoline powered engines tend to produce a lot of power for their size, which for a six-seat vehicle seems like a good choice. However, if you do not carry at least two or more passengers all the time, this extra power can lead to dangerous speed, making the craft hard to control and unsafe to operate. Electric motors can produce steady power for several passengers but are easier to throttle to safe operational speeds. Ultimately, the best design will cap speed to less than 15 miles per hour.
Frame and Suspension
The frame choice for a six-seat kart should provide enough structural integrity to withstand an impact at maximum speed and load, yet at the same time be light enough not to crush occupants if the craft overturns. If the device is designed for higher speed operation, you will need to balance those needs with the need for a roll cage. Keeping the suspension low to the ground minimizes those safety issues and provides better handling, but creates a problem with clearance, limiting the environments in which you can operate the craft.
Control and Safety Mechanisms
The higher the operational speed of the vehicle, the more robust the control mechanisms for the craft will have to be. It might be tempting to use a form fitted plastic steering wheel mounted to the control shaft, but you should pick a more durable metal wheel with rubberized handles. Plastic steering wheels can shatter during a collision, forcing the bare metal column into the driver's chest. You should choose brakes capable of safely controlling the speed in a short distance under a variety of conditions, especially if you are utilizing the craft for off-road operations. You should bolt seats to the frame and ensure all passengers have safety straps and seat belts.
The Best Six-Seaters
A six-seat kart poses a number of safety issues. Multiple passengers create significant momentum, making the prospects of safe control and operation difficult hurdles to surmount. Additionally, the additional seating requires reinforcement of support structures and extension of the body. The only way to minimize momentum and aid control is to limit the top speed of the vehicle. By lowering the top operational speed, you relax the requirements for impact resistance and support and provide a safer ride for all. Ultimately, the best six-seat go kart will resemble a multiple passenger golf cart in form and function.