I think farings & such are very practical. Just a word of caution on any thoughts of home built aerodynamics.
There's no question of the effects of aerodynamics & streamlining on vehicles. One must be more than careful that the same aero effects don't cause unwanted lift. Whether air foils, tunnel effect or an aero enclosure, if lift is accidently caused the results can be disastrous & deadly.
http://lsrdeaths.webs.com/191039.htm
Above link: In 1937 Britain's Eric Ferinhough attempted to regain his Land Speed Record on a supercharged Brough Superior motorcycle. It ended in tragedy when he suddenly left the track at 170 mph. The resulting crash threw him 30 yards, he later died from injuries. Look closely at the pictures at the link above & see the opening at front fender aero, and at rear fender leading edges. No real surprise he became airborne with those lifting scoops at that speed!
Above link: In 1938 AutoUnion was trying for the Land Speed Record in their aerodynamic streamliner driven by Bernd Rosemeyer. The entire body was enveloped in hand-hammered aluminum panels, similar to an airplane. They made a mistake in overlapping the sheets from rear to front. This meant the sheet's leading edges were exposed & rivettted down, while trailing edges were overlapped.
At speed a tire & wheel disintegrated and air then caught under the leading edge of a damaged frontal sheet which began to peel back. This unexpected aerodynamic lift catapaulted the car into the air and it cart-wheeled end over end at well over 250 mph. Rosemeyer lost his life in the crash. Some witnesses of the time said the aero body sheet tore loose first, and as car lifted the tire was cut, blew and wheel was thrown off. I believe the wrong car is pictured on the 'Speed Record deaths' page, should be the Hans Stuck Sr. Type C car at this link:
http://en.wikipedia.org/wiki/Auto_Union
Do be careful?