Hi,
Re: http://wiki.contextgarden.net/Using_Graphics#Image_Conversion
I recommend using rsvg-convert instead of inkscape. For example:
wget http://en.wikipedia.org/wiki/File:Inkscape_0.48.2_with_Red_Gallardo.svg -O car.svg time rsvg-convert --format pdf car.svg --output car-rsvg.pdf time inkscape --file=car.svg --export-pdf=car-inkscape.pdf --without-gui
wget http://openclipart.org/download/people/TheStructorr/TheStructorr_Lamborghini... -O car2.svg time rsvg-convert --format pdf car2.svg --output car2-rsvg.pdf time inkscape --file=car2.svg --export-pdf=car2-inkscape.pdf --without-gui
Here, inkscape is slightly faster yet produces slightly larger files.
inkscape 0.48.4 r9939 (Jan 22 2014) rsvg-convert version 2.40.2
More importantly, inkscape renders incorrectly. The horizontal and vertical rule marks are missing in the first image. The gradient shadows are missing in the second image, and the grill is incorrect (looks like a layer order issue).