<http://schema.org/headline>
"2011 Porsche Boxster Spyder vs. 2011 Audi S4"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.roadandtrack.com/new-cars/car-comparison-tests/reviews/a17389/2011-porsche-boxster-spyder-vs-2011-audi-s4/>