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In re: the OP (perhaps many of these points have been raised, but I didn't see 'em all at once).
What you have to understand about laminar flow is that it's VERY unnatural--air wants to go turbulent at speeds and sizes relavant to motor vehicle travel. To sort of "cheat the air," aero-engineers have created the (NACA, NLF) natural laminar flow airfoils. These have pressure distributions whereby the top-side pressure gradient increases to a maximum fairly far back on the airfoil (and are thus typically characterized by max thickness fairly far back on the wing chord). These allow up to around 70% (as of the printing edition of my Theory of Wing Sections) **under ideal testing conditions, and across a narrow range of coefficient of lift**.
What this means is laminar flow is very hard to achieve, to the point that a riveted aircraft skin--even flush rivets--will most likely "trip" laminar flow and you'll not realize the benefits thereof. That's why most of the achieved laminar flow is from composite wings (creating the term "fast glass.") Grumman Co. went as far as to make it's AA5A/AG5A light aircraft with BONDED aluminum wing skins--but manufacturing variances and wing flex in flight were too significant to realize much laminar flow.
Also, "surface roughness" (akin to frost or just an unwashed, unwaxed surface) will kill NLF, too.
What that means for the home aero-modder is twofold:
1) "Fuggedabout" laminar flow, unless you have a machine shop capable of meeting or exceeding Boeing/Airbus standards. Consider Basjoos' AeroCivic: he did all the right things, got great economy...but "fit and finish" wasn't really up to Boeing standards...or even Chevy standards. Surface roughness out the wazoo!
A perusal of the site shows that rough fit+finish is the rule, not the exception here, thus chasing after NLF is waste of energies that could better applied to maintaining attached turbulent flow across as much of the vehicle as possible.
Not only will you lose NLF over surface roughness, airflow through the unsealed gaps in the hood will, too (how the OP intends to maintain NLF aft of the spinning wheels is anybody's guess), as will smashed bugs on the leading edge, etc, etc.
Furthermore, if you really want NLF (and have the CNC machinery to prove it), you can't just make your car's top+bottom "kinda look like a wing": no, you have to get a NACA NLF-series airfoil and match your car's profile EXACTLY to that specific airfoil (note that most airfoils are turbulent across the majority of the chord, yet those planes fly just fine).
2. You don't really need laminar flow, anyways. Note...all those planes flying just fine with turbulent-flow airfoils, as well as Basjoos mentioned previously. You can probably get north of 100MPG with optimized, turbulent, attached flow and a decent engine...and if that's not good enough, well, THEN start looking into CNC lathes and such.
Actually, turbulent flow is good in that it adheres to curves better without detaching...if one DID actually make a NLF-auto, it would likely be impossibly long!
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