Nissan Sileighty

The name comes from a combination of "Silvia" (the front half) and "180SX" (One-Eighty, the rear half), referring to the two halves of the cars that are used to create the vehicle. Conversely, the reverse is true for "Onevia", which in this case stands for "180SX" (One-Eighty, the front half) and "Silvia" (the rear half).

Sileighty (or abbreviated as "Sil80") is a common nickname among many enthusiasts for the Silvia-180SX combination; the same is true for Onevia, which is the nickname for the 180SX-Silvia combination. Though the actual name of the car remained as 180SX (and as Silvia for the Onevia), Nissan did register the Sileighty nickname in 1998 as a trademark, making it an official name under the company.

It has become well-known among the Japanese hashiriya (street racers in Japanese) that the origins of what would eventually become the Sileighty came about when early street racers had 180SXs with damaged front-ends during races or practice runs. To save on costs for front-end repairs on their 180SXs (at a time when the 180SX front-end with the retractable headlights was too expensive to obtain by most street racers), many of them would most likely replace them with the ones from an S13 Silvia due to the inexpensive nature of the S13 Silvia front-ends. Another factor was to replace the retractable headlights of the 180SX with the fixed relampable headlights of the S13 Silvia in order to save on weight.^[2]

The earliest documented example of such a modification was featured on Option on its August 1989 edition during the "TEST on ROAD" section where a relatively new 4-speed automatic 180SX with some modifications (e.g. boost upgrades) was outfitted with the front-end of an S13 Silvia by a tuning shop in Tokyo. It was therefore dubbed as the "Silvia 180SX", as the Sileighty name had not yet been coined at the time.

Despite the arrival of the S14 Silvia in late 1993, most street racers opted to stick with the S13-chassis Silvia and 180SX on the grounds that the S14 Silvia was larger in size (which affected initial sales and popularity due to the higher road taxes for Japanese buyers imposed by the Japanese government regulations for vehicle body size), and had limited compatibility with parts from the S13-chassis cars due to design differences. At this time, the trend of modifying the 180SX to use the S13 Silvia's front-end started to gain popularity, leading to the creation of the Sileighty as it is known today.^[2]

Soon after the Sileighty's popularity, another modification appeared that used the 180SX's front-end onto the S13 Silvia dubbed as the Onevia, however it did not receive the same popularity as the Sileighty due to its use of a retractable headlight system that most could not afford at the time (which also added a bit of weight to the vehicle) as well as it being considered "ugly" by most if not all owners; the Onevia as a result was relegated into complete obscurity for aesthetic purposes by those who wanted the notchback coupe model of the 180SX.^[3] However, Nissan in North America did offer a coupe model for their domestic version of the 180SX, the 240SX, which simply transplants the 240SX's front-end onto the body of an S13 Silvia; this model predates the Onevia modification produced by Japanese street racers in their home region as it was sold as early as 1989 when the 240SX launched in North America.

The Sileighty is notable in popular culture both nationally and internationally, being featured in media such as Initial D (where it was featured as the car driven by Impact Blue drivers Mako Sato and her navigator Sayuki during the first few chapters in the manga and in the First Stage anime), Gran Turismo (where it was featured as the unofficial model based on the one featured in Initial D in the first two games as well as the Kid's Heart version in later games), and Tokyo Xtreme Racer (where the Sileighty appeared in Tokyo Xtreme Racer: Zero, Tokyo Xtreme Racer: Drift and Tokyo Xtreme Racer: Drift 2 and the Onevia appearing exclusively in Drift 2). In Japan, it gained prominence following its appearance in Motor Magazine Co.'s Holiday Auto biweekly automotive magazine and as a model car in Tomy's Tomica line.^[e] The Sileighty also spawned off a parody vehicle featured on Option known as the "Nissan Celeighty" (日産・セルエイティ), featuring a literal cut and shut (or nikoichi (ニコイチ), meaning "two-in-one" in Japanese) vehicle created by welding the front-ends of a Toyota Celsior (Japanese model of the Lexus LS 400) onto another car; this car also appeared in Atsushi Arino's manga, Kan Touge.

The S13-chassis Nissan Silvia and 180SX, of which the parts of the Sileighty is based on

The S13 Silvia and 180SX use the same body structure and chassis despite being two separate cars, allowing for a much higher parts compatibility between them. As such, many of the components such as the engines, brakes, suspensions, etc., can be used interchangeably with each other, which also makes swapping the front-ends of both cars much more convenient.^[2]

The Sileighty modification takes this concept into play by transplanting the front half of the S13 Silvia (such as the bumper, fenders, hood, and headlamps) into the body of a 180SX, creating a hatchback version of the S13 Silvia that was never officially released by the original manufacturer.^[3] These same modifications can also be applied into the 240SX hatchback sold in North America as well as the RS13U 200SX hatchback sold in other countries such as the United Kingdom among others.

As the S13 Silvia front-end is shorter than the 180SX/200SX/240SX, the overall length is reduced by 4 cm (40 mm) after performing the swap, equating to about 448 cm (4,480 mm) in total length. This can potentially violate the Japanese Government's Road Vehicle Act of 1951 on safety standards for road transport vehicles (Ministry of Transport Ordinance No. 67 of 1951) if it is driven on public roads (i.e. cars must be at least 12 m (1,200 cm; 12,000 mm) long or less for it to be considered roadworthy),^[4] so it is often recommended that a public inspection must be conducted so that a new vehicle inspection certificate can be issued or by equipping aftermarket parts to ensure that it is roadworthy by keeping it near the original lengths of the vehicle or even exceeding it. Despite the overall similarity, it is not what is considered by some as a true "cut and shut" or nikoichi (ニコイチ) vehicle, as the overall body shell of the car remains untouched.

Though applying the S13 Silvia's front-end onto the body of a 180SX hatchback is a common modification, there is a reverse method to this approach that by using the front-end exterior parts off of a 180SX/200SX/240SX into the body of an S13 Silvia, another unique modification can achieved known as the Onevia, which is essentially the opposite of the Sileighty. While this variation was never officially sold in its home region of Japan nor in other countries of the world, it was officially sold in North America as the 240SX coupe and convertible, where the 180SX/240SX front-end is used on an otherwise S13 Silvia coupe body to create the coupe and convertible models sold in that region. On the other hand, applying the S13 Silvia front-end onto the body of a North American 240SX coupe and convertible essentially creates a left-hand drive version of the S13 Silvia that was never officially sold in North America (or other countries in the world using left-hand drive configurations), sometimes known as a "JDM conversion".

While the Sileighty most commonly refers to a modified 180SX with the S13 Silvia front-end, variations of this approach using the front-ends of the vastly-different-in-design S14 and S15 Silvia models have also been produced. The variant with the S15 front-end is sometimes referred to as the "strawberry face" Sileighty due to the fact that the number "15" in the model code of the S15 Silvia also means "strawberry" in Japanese. A similar rendition of this approach can also be found on the S14 Silvia, which can be modified to use an S15 Silvia front-end. Enthusiasts would sometimes label these modifications with designations such as "S13.5", "S14.5" or similar for the purposes of brevity, with the number following the dot representing the front-end conversion and the corresponding model number before it representing the actual chassis of the car in which the front-end swap is performed on.

Unlike the S13 Silvia, however, the S14 and S15 Silvias have significantly different body structures from each other including the 180SX, and thus requires several modifications to the body panels (and sometimes the body structure itself) before they can be properly applied onto the 180SX (the same applies to the S14 Silvia example above). However, due to the high popularity and demand of the S13-chassis cars, aftermarket parts manufacturers have made conversion kits for creating these types of vehicles.^[5] Though this makes it somewhat similar to a true "cut and shut" or nikoichi (ニコイチ) vehicle in that the body structure has to be modified in order to accommodate the new parts as compared to using parts that shared the same body structure, the S13, S14, and S15 cars technically shared the same platform despite having three different body styles, and so it is not truly considered to be one as the rest of the body structure remains untouched much like the Sileighty modification.

• Nissan Silvia — Original notchback coupe model of the S13 with fixed headlights, of which the front-end of the Sileighty is based on
• Nissan 180SX — Three-door hatchback model of the S13 with retractable pop-up headlights, of which the middle and rear portion of the Sileighty is based on
  • Nissan 200SX — European version of the 180SX
  • Nissan 240SX — North American version of the 180SX, of which its coupe body style for the S13 is based on the Onevia