There are tons of regulations and safety standards that all cars must pass before they can be shipped and sold in America. Whether they were too unsafe their engine was too big or other unforeseen issues, these cars didn't quite make the government cut.
Toyota Hilux

World renowned for being practically indestructible, the Hilux is one of the most dependable and reliable trucks on the market, but don't expect to be driving one any time soon. The Hilux has a turbo diesel engine and the EPA's rules for air quality won't allow it to be imported.
Land Rover Defender 90-110-130

Although the Defender looks like a beast, the engine was deemed unreliable and it failed to meet several regulations.
2002 Morgan Le Mans ’62 Prototype

These cars were created to be exactly the their '62 predecessor, which lead to quite a few safety concerns; the main onebeing that there is only one door handle on the car.
1993 Jaguar XJ220-S

The Jaguar XJ220-S was a street-legal version of their XJ220-C racer. The engine produced 690 horsepower, which unfortunately put the car over regulation max for street cars.
1999 Nissan Skyline R34 GT-R V-spec

The Skyline was one of the first cars to display the various statistics about the car during operation, and there was even a computer jack located under the drivers seat that could transmit information. All that technology loaded inside has constantly kept this car off American soil.
Lamborghini Strosek Diablo

Designer Vittorio Strosek modified the Diablo body to try and make it stand out more. Strosek raised the side mirrors, changed the bumpers and gave it new headlights; all of which led to the vehicle not being allowed in the United States.
Nissan Patrol

While it looks like a pretty rugged vehicle, the majority of the Nissan Patrol's safety features are not up to code.
1996-2001 Lotus Elise S1

This infamous Lotus weighed in at a lighter 1,600 lbs, which made it a nimble and zippy choice. However, Lotus elected to build the car sans power steering and without a break servo, which did not meet American safety standards.
1990 BMW M3 Sport Evolution III

The engine in the M3 was too long to fit in an "everyday" car, and as a result the car failed many regulations.
Diesel Toyota Land Cruiser Truck

The Land Cruiser is a staple in Japan and Australia, known for it's rugged and massive size. Sadly, this is another tragic tale of being too large for it's own good.
Ford Focus RS500

A Ford Focus? How could this be banned? Well the powerful engine inside holds this bad boy outside the border. The 350 hp it pumps out causes major safety concerns for such a small car.
1995 Audi RS2 Avant

The RS2 Avant cannot be imported, not even for show! The 2.2L 5-cylinder 20v turbo engine can hit speeds over 150 mph, which makes this car unusable on the streets.
TVR Sagaris

As beautiful as the Sagaris is, you will understand why this car isn't allowed in the USA. The Sagaris doesn't have ABS or airbags, pretty hard to pass regulations without those!
Volkswagen Amarok

Another extremely well-designed vehicle that gets praise from all other countries — except America. The Amarok lacks in some of the vital safety features needed to be regulated. And with the recent flak over VW, were sure cars like this won't be admissible for a while yet.