Every motor show brings a glittering array of concept cars for every passerby to stop and coo over. They're a chance for designers to let their imaginations run wild, for companies to project a vision of future, as well as teasing customers with the excitement to come. Yes, this year's retail model might be a bland facelift of what you've seen before, but there are concept models making promises that are rarely kept.

But what if they did keep those promises? While there are plenty of real cars on the show floor at the IAA 2013 Frankfurt Motor Show, all the concepts got us thinking. What if all these cars came to life? What sort of cars would we be looking at?

There's a distinct theme to current concept cars. The bubbly SUV that suggests you're fun and sporty, such as the Citroen Cactus concept, unveiled at IAA 2013, or the Renault Captur concept, originally revealed in 2011 that's reflected in the reality of the Captur model Renault has recently launched.

The Smart FourJoy is again bubbly and sporty, as much a lifestyle statement as it is car. Rarely is there a regular hatchback to be seen.

Citreon Cactus

The Citroen Cactus concept

BMW runs further with the sporty theme in its Concept Active Tourer, slipping a rack for two road bikes in the back, and Lexus and Jaguar follow suit, going big, if a little more serious, with the Lexus LF-NX and the Jaguar C-X17.

On the sportscar side, however, you've got the likes of the Renault DeZir that appeared in 2010 and Peugeot Onyx from 2012, pushing that sleek future angle, along with the likes of the Nissan FriendMe, which expands to four seats, originally unveiled at the Shanghai Motor Show 2013.

There's not a conventional seat to be found inside this selection of concept cars. Renault has opted for tensioned elastic for its Captur concept model and what looks like a giant foam footprint for its DeZir coupe concept. The DeZir, says Renault, offers a shared seat that "celebrates the intimacy of a romantic meeting", we're hoping that does't mean squelchy.

Renault Captur concept

Citreon's Cactus puts a bench seat in the front finished in natural materials, which is relatively old school, but is thinking along the same lines as Renault's intimate seating, as is the reported "lounge" seating of the Nissan FriendMe. Sitting just won't be the same again.

And while the Ford S-Max concept might look pretty normal in the seating department, it wants to monitor your body systems and collect biometric data: being connected, it seems is extending to the driver's body too and doesn't just offer Spotify and Google Maps.

The Ford S-Max concept isn't the only thing that wants to keep track of your body. Nissan has announced the Nismo Watch, which is still very much a concept. But, via a smartphone app, it wants to feed you all sorts of data. It's all about wearable tech these days you see, and having the information to hand, whether that's about your car or your body.

Nissan Nismo Watch Concept

Nissan also plans to extend this technology, which is based around the monitoring of Nismo race drivers, and it has set it's sights on biometrics, aiming to detect when you might be getting tired, or when you're under stress. 

You might have thought that being connected to the internet was enough, but the cars of the future want to be connected to your body too.

The future is all about efficiency and we're looking at cars that are more efficient with a range of hybrid engine types, like the Citreon Cactus' HybridAir system, or the Smart FourJoy's electric motor. Electric cars are definitely in focus, but there are still some that want to give you a straight ICE: the Ford S-Max concept will get a 1.5-litre EcoBoost engine. We get the feeling that the Ford is closer to reality than some others.

It's no secret that we think cars with doors that open upwards are cool. Just look at the Mercedes SLS or the McLaren MP4-12C. What these cars put into reality, also appears on these concepts. Renault opts for upwards opening doors on both concepts, as does the Subaru Viziv. Nissan's FriendMe opts for a coach-style door with pillarless design.

Nissan FriendMe concept

There's a distinct lack of door handles, but then they are rather ugly, aren't they?

Going one step further, the Smart FourJoy ditches the doors altogether: it's more like a beach buggy (pictured at the top).

But having been through all these concepts, there's something that's bugging us and that's BMW. Step onto the BMW stand at the Frankfurt Motor Show and the BMW i cars steal the concept show. They look like concepts, they exhibit the characteristics of concepts, yet both the BMW i3 and the BMW i8 are production cars.

The i3 gives you the sporty, bubbly, SUV with coach-style doors, with an electric motor and seats finished in naturally resourced earthy materials. The BMW i3 ConnectedDrive app will monitor your car and feed that to you through an app, it's just not quite monitoring your heart rate, yet.

On the sports car side of things, the BMW i8 has now officially launched, giving you the ultra-modern looks, and those funky upwards opening doors. There's an advanced electric hybrid power system and plenty of in-car connectivity through the app. 

So while many manufacturers are showing off concept cars, it feels like BMW are already making them. Ironic then, that it's own BMW Concept Active Tourer is a rather pedestrian-looking affair.