One thing I've learned over my nearly 30-year streak of attending the North American International Auto Show in Detroit, is that a concept vehicle — this extravagant, eye-catching thing — was guaranteed to disappoint you in some way when (and if) it made it to production. Concepts more often than not are design exercises, or ways to start sketching out the possibilities of a new model. But when it comes to actually making these concepts come to life, engineering and physics tend to get in the way and change things, sometimes drastically. Sucks, I know.I asked you over the weekend what concept cars spawned the most disappointing production vehicles, and I happened to notice a trend in the answers. Not for any one specific car, but many of your answers came from Detroit — General Motors, Stellantis, and Ford. Only a few foreign models made it into the comments. Is the reasoning because American automakers tend to dream a little too big? Does reality rear its ugly head when it comes to putting real parts into these cars and they can't afford to make the concept a reality? Or are foreign automakers just better at getting a concept closer to the production car? This was simply an observation, but many of you seem incredibly disappointed by the lot of their promised cars. With that in mind, here are some of the concept cars our fellow Jalops thought spawned the most disappointing production vehicles.AdvertisementAdvertisementRead more: These Car Brands Aren't Making It Through The Next RecessionChevrolet VoltNAParis / Wikimedia CommonsThe original Chevy Volt concept. It was a legitimately cool-looking car. This could have been an EV statement from Chevrolet.ANDNissan Chill-Out concept to Nissan Leaf? Hang-Out to Kicks wasn't great either, but not as bad.Though in terms of the biggest audience disappointment, I'd say Chevrolet Volt. The Volt concept came out right around when GM was in the doorstep of bankruptcy, and right after Toyota momentarily dethroned GM as the world's biggest automaker.The Volt was that brash, macho, and confident anti-Prius, a new kind of high performance hybrid/EV that was supposed to turn around GM's fortune. Everyone was excited and the concept highly publicized... and then the production version looked like a me-too Prius. The bankruptcy came soon after.From JohnnyWasASchoolBoy and VarPontiac Trans SportAdvertisementAdvertisementPontiac Transport minivan of around 1986... that thing looked cool. The resultant van... oh my, what a disappointment.ANDI remember – it was 1989 I think – seeing that concept car at the Philly Auto Show and it was one cool looking minivan! One more upvote for you – GM could have had a massive hit if the Dustbusters were more like the concept. Then again, a wheezy V6 and 3 speed automatic at launch didn't help matters as well.From BuddyS and Xavier 96Jeep GladiatorIG-2000 / Wikimedia CommonsThe Jeep gladiator concept, 2 doors bedside spare, classic style grill and we just got a 4 door Wrangler with a bed slapped onAdvertisementAdvertisementANDEvery year, Jeep rolls out some absolutely lust-worthy concepts. Every year! Do they ever bring them to market? Noooo!From JaredOfLondon and RollerrobbFord Interceptor ConceptFordFord interceptor concept. Somehow it became the 500/Taurus.From BrandonSubaru WRXzombieite / Wikimedia CommonsAdvertisementAdvertisementEvery single Subaru WRX concept vs. the real car they released in the last 20 years.ANDI'm still dying on this Hill. Still to me the best concept from them, and the production vehicle that followed was realizing you had beer goggles.ANDomg omg you know how apparently many men think about the Roman Empire every day?Well not a day goes by that I don't think about the massive disappointment when Subaru releasedTHIS... (See reply for next photo)From fabey, Agon Targeryan, and DJPJeep RenegadeOverlaet / Wikimedia CommonsAdvertisementAdvertisementHow many of y'all remember what the Jeep Renegade was supposed to be? Honestly, that's a great looking (maybe a little overdone but given the mission, I'll give it the thumbs up) offroader. Of course the doors could never pass side impact standards, and the two seats limit usefulness, but Jeep could have made this as a "Miata for the mud" – a fun roundabout that is useful offroad. I think it could have done quite well.And I don't need to remind anyone here about the wet fart that Jeep introduced, cost cut to death using leftover Fiat and Alfa parts, and it limps along to this day, condemned as the $29/day rental special.From Xavier96Toyota FT1 Concept (Supra)The Toyota FT1 was gorgeous with great proportions. The Supra that showed up looked like a squished, cheapened version of that show car.From: Gordon S.Jaguar XJ220Haynes Motor MuseumAdvertisementAdvertisementThe Jaguar XJ220, supposed to be a V12 monster with scissor doors and all wheel drive Lambo kiler. Became a regular V6 powered, regular doored, grand tourer with regular RWD, suitable for turning up at the golf club in.From SkefflesPontiac AztekKing Rose ArchivesPontiac Aztek. What started as something interesting (though not for me; I'm not an SUV fan) turned into an attempt to make a minivan go off road. It should have stayed off road.From Joe StrickerOk, I may be the only human in existence who might have loved the Aztek, and I will happily die on that hill. But in all seriousness, if GM hadn't GM'ed the Aztek, would you have been more willing to own the concept model?Want more like this? Join the Jalopnik newsletter to get the latest auto news sent straight to your inbox, and follow us or add us as a preferred search source on Google.Read the original article on Jalopnik.