Interestingly, this year's Frankfurt Motor Show had more exciting concept debuts than actual production cars. Sure the Porsche 918 Spyder and BMW i8 are ridiculously cool, but this year's concept crop from several automakers were sexy, daring and even just a little bit bonkers (yes, we're talking about you Lexus LF-NX Crossover). In no particular order, we've gathered up our list of the top concepts from Frankfurt 2013. Not all will reach production in their current design form, but a few look to be nearly ready to hit the road.

If this is what Mercedes has in mind for its upcoming S-Class coupe, then we have absolutely no complaints. This S-Class Coupe Concept is nothing short of gorgeous. It just looks incredible from every angle and its interior is equally classy. Aside from those narrow side mirrors and a few other odds and ends, this thing looks nearly production ready. But the best part about it is that a V12 engine can easily fit under its long hood. Just imagine what a future AMG S-Class Coupe will be like.

We're still debating whether we like Audi's newest Sport Quattro Concept or the one it unveiled back in 2010 at Paris. Nevertheless, we're awfully glad that Audi hasn't given up on a tribute to its legendary rally racer. Word has it that there's room in the Audi lineup for something in between the TT and the R8. The Sport Quattro may be the answer, but a production version will likely be very limited in number.

Jaguar has been talking about a possible SUV/crossover for some time now, and the C-X17 concept is what it came up with. Sporting signature Jaguar headlights and grille, the C-X17 also appears to be nearly ready for production. The question is whether its design is good enough in light of major competition coming from Jaguar's own sister brand, Land Rover and its Evoque. Still, a production-spec C-X17 could be a huge money maker for Jaguar, and when there's good cash flow, that means more unique versions of the F-Type and other models.

Perhaps this is Volvo's clearest message so far that it's keen to take on the likes of BMW's 7 Series. Although the Volvo Concept Coupe is just that, a coupe, there have been rumors coming from the now Chinese-owned Volvo that adding a couple of rear doors won't be hard. So is this concept a preview of the next-gen S80 sedan or something else entirely?

Opel is looking to revive itself in a way that'll keep it relevant in Europe, and the best way to do is to come up with a truly original and stunning design language. With the new Monza Concept, it appears GM's European brand has done exactly that. Although those gullwing doors are a production fantasy, the rest of this concept's styling is quite doable. GM also has a habit of turning Opels into Buicks, and if this formula continues, then perhaps a production-spec Monza could one day become a proper Buick coupe.

Honorable Mention goes to the Lexus LF-NX Concept not because it's all that pretty (far from it), but simply due to the fact that Lexus had the balls to do it in the first place. It almost looks like it'll slice your arm off if you walk too close to it. While a production version is entirely possible, we hope Lexus can tone things down a bit without making it look bland.