User:Average/Industrial Design
Industrial Design, generally deals with the relationship between a machine and the world. A companion to ergonomics which deals with the relationship between the machine and the human.
Shape of profile for drag considerations will depend on the relationship to speed, the heaviness of air, and the speed of sound. The latter produces an envelop of certain (i.e. calculable) size in front of your vehicle. This will be useful in calculating the amount of air (and heaviness) that has to be pushed or moved away as it moves. In theory, you could collect water as you move through the air, via a metal grid-type collector. That's on Earth.
Aerofoils (to create pressure differentials on one side from another), designed to create down-forces, are generally superfluous, as most vehicles are plenty heavy for their speed and rubber has plenty of traction. However, do note that most vehicles are creating lift from the fact that air above the vehicle is going faster than the air underneath it. So you may have to counter-act this force. Loose approximation is design in aerodynamic components after speed (in mph) exceeds weight (in lbs). An aerofoil adds drag.
Consider a internal-combustion engine's needs for air. Air needs filters both from water and from dirt to avoid wear on cylinders and dilution ofgas/oil. Crossflow crankcase ventilation can remove the concern for water, as it should boil off and flow out. The less the engine has to work to get air, the more efficient it is. So air scoops that create pressure at the intake manifold are helpful. In order for this air flow not to get constricted by your air filter, you need larger surface area. There's no need for this to be inside the engine compartment, where it obscures access to servicable engine components. So, move it forward, where it can be easier to access. Make it two-pass: a metal screen for collecting water and large debris, and a two regular filters, on either side.
A smaller air filter is generally a less efficient one, try breathing through one. See how much area you'll need to feel no constriction of air. A gas mask for humans has about four inch diameter filter for breathabiltiy. Your engine probably needs 10x the surface area.
Exhaust manifolds can be fluted to allow more degrees of freedom for handling exhaust speeds. Mufflers shouldn't be needed in a good design as you should be harnessing most of that energy, not losing it.