Not if there is contraband in plain view or if they get consent or if they otherwise have probable cause to believe that there is illegal contraband in the car. Also, if they arrest someone for a valid cause (ie. outstanding warrant) they can perform a search incident to arrest of the person arrested and the area of the car in his immediate reach which could have a weapon available.
I don't carry anything illegal in the Vette (actually I don't own anything that could be remotely considered illegal).
However, the Vette is filled with bits of this and that from the space program (ALL ACQUIRED LEGALLY) such as a meteorite, three axis Inertial Nav unit, carbon-carbon skin, MLI, shuttle tile material, sensors, PMTs, thermal OSRs, CCD focal plane assembly, honeycomb skin, solar panels, flight computer, spacecraft panels, mono-propellant fuel line, RF cable, solar sail material, Astro-Quartz, x-band dish antenna, microwave omni antennas, flat ceramic microwave antennas, an RF subsystem assembly, blue nomex flight suit, Carbon/Kevlar clean-room suit, Neutron detectors, Vela Satellite sensor assembly, Indium foil, Kapton, Mylar, Titanium struts, Cray 3 computer boards, ceramic parts, core memory arrays, waveguide, 76GHz microwave assembly with feed, ring laser 3 axis gyro assembly, beta cloth, gamma and xray detectors, etc.
I take this stuff around to schools so kids get a chance to handle actual spacecraft hardware. :-)
(at least four of these items have been flown in space)
Wonder what a LEO would think as all that got piled alongside the Vette?