If anyone is looking for a more "complete" list. Scraped from supercars.net. I found a couple like Skunk2 and SLP that weren't really manufacturers but aftermarket companies that modified other cars. If anyone wants to refine this list further I believe its a good one to go off of.

Abarth, Abt, Ac, Ac Schnitzer, Acura, Alfa-romeo, Allard, Alpina, Alpine, Alvis, Amg, Arden, Ariel, Ascari, Aston Martin, Auburn, Audi, Austin-healey, Auto Union, Artega, Apollo, Aac, Abd, Adrenaline, Aeon, Alan Mann, Alba, American, Amilcar, Ark, Arash, Asc, Asl, Asma, Ats, Auburn, Austin, Autech, Bac, Baldwin Motion, Bertone, Ballot, Bentley, Benz, Bizzarrini, Bmw, Brabus, Bugatti, Buick, Cadillac, Callaway, Carlsson, Caterham, Chevrolet, Chrysler, Citroën, Cisitalia, Chevron, Castagna, Cizeta, Caparo, Continental, Cooper, Cord, Corvair, Courage, Daimler, Datsun, Dauer, Delage, Delahaye, Detomaso, Dino, Dodge, Dome, Donkervoort, Duesenberg, Dacia, Daewoo, Daihatsu, De Dion-bouton, Delaunay, Delorean, Denzel, Derby, Desoto, Detroit Electric, Devin, Devon, Diatto, Dinan, Dkw, Doran, Dp, Dreker, Dual-ghia, Dupont, David Brown, Devel Sixteen, Edag, Edo, Edwards, Elfin, Elva, Eagle, Echidna, Emme, Enizio, Epsilon, Ermini, Etud, Eunos, Evans, Evolve, Exagon, Elemental, Ferrari, Fiat, Fioravanti, Fisker, Ford, Fabcar, Facel Vega, 9ff, Faraday, Fifteen52, Flajole, Foose, Forced Fed, Facetti, Factory Five, Farbio, Farman, Farboud, Fenix, Fab Design, Fenomenon, Frazer Nash, Fronty, F.r.p, Fswerks, Fuore, Galpin, Geiger, Gemballa, Ghia, Ginetta, General Motors, Gordini, Gpower, Greenwood, Grmn, Gumpert, Gaaco, Geely, Genaddi, Gigliato, Gillet, Giugiaro, Glasspar, Graber Cars, Greddy, Gta, Genesis, Gillet, Gmc, Hamann, Hartge, Hennessey, Hispano-suiza, Holden, Honda, Hommel, Horch, Hpd, Hsv, Hurst, Hongqi, Hafei, Hasport, Hbh, Heynsdyk, Hks, Hunter, Hoermann, Hooper, Hotchkiss, Howell, Hrg, Hudson, Hulme, Hyundai, Heuliez, Imperial, Infiniti, Innotech, Isdera, Iso, Isotta, Isuzu, Italdesign, I.de.a, Ied, Imola Racing, Impul, Imsa, Intermeccanica, Intrepid, Invicta, Iceni, Icona, Iconic, Italmeccanica, Jaguar, Jeep, Jensen, Javan, Jetstream, Jimenez, Jiotto, Joest, Jba, Jac, Kaiser-darrin, Karmann, Katech, Keating, Kellison, Kepler Motors, Kia, Kicherer, Kleemann, Koenigsegg, Koenig-specials, Kremer, Ktm, Kurtis, Karma, Lagonda, Lamborghini, Lancia, Lexus, Lincoln, Lingenfelter, Lister, Lola, Lotus, Laboratorio, Lanchester, Land Rover, Lang-cooper, Laraki, Lasalle, Laurin & Klement, Lea Francis, Leblanc, Lightning, Ligier, Lj Garcia, Local Motors, Locomobile, Locus, Loder1899, Lohner-porsche, Loremo, Lorraine-Dietrich, Lotec, Lumma, Lykan, Lloyd, Lobini, Lucid, Luxgen, Magna, Mallett, Mamerow, Mansory, March, Marcos, Marmon, Marussia, Maserati, Mastretta, Matech-ford, Matra-simca, Maybach, Mazda, Mazel, Mazzanti, Mca, Mcculloch, Mclaren, Mcv, Mega, Melkus, Melling, Mercedes, Mercedes-amg, Mercedes-benz, Merc-knight, Mercer, Mercury, Mg, Miller, Minerva, Mini, Mirage, Mitsubishi, Mitsuoka, Mobsteel, Momo, Monteverdi, Mooncraft, Moretti, Morgan, Morris, Mosler, Mr Norm’s, Mrt, Mso, Mtm, Mugen, Mullen, Multimatic, Muntz, Murena, Nash-healey, Nismo, Nissan, Noble, Novitec, Napier, Nash, Neuspeed, Nickey, Norman E. Timbs, Nova, Neri & Bonacini, Oettinger, Oldsmobile, Old Yeller, Olsbergsmse, Om, Opel, Orca, Oreca, Osca, Osella, Packard, Pagani, Panhard, Panoz, Peugeot, Pierce-arrow, Pininfarina, Plymouth, Pontiac, Porsche, Prodrive, Puma, Ppi, Pgo, Peerless, Pegaso, Perana, Perrin, Pescarolo, Picchio, Pierce, Pilbeam, Piontek, Premier, Prince, Prindiville, Prost, Proton, Psi, Polestar, Panther, Parradine, Piper, Pirrung, Pratt & Miller, Quant, Qvale, Qvick, Radical, Reiter, Renault, Renntech, Riley, Rinspeed, Rmr, Rolls-royce, Roush, Rover, Ruf, Racing Dynamics, Radford, Re Amemiya, Redline, René Bonnet, Revenge, Reyard, Reynard, Rickenbaker, Rk Collection, Rlr, Roewe, Ronart, Ronn Motor, Roock, Roos, Rossi, Rossion, Royal Excellence, Rsr, Rtr, Rometsch, Russo-baltique, Ruxton, Rezvani, Ram, Rimac, Ranz, Saab, Saleen, Sbarro, Scarab, Scion, Seat, Shelby, Singer, Siata, Simca, Sms, Speedart, Sportec, Spyker, Ssc, Startech, Steeda, Stola, Strosek, Stutz, Subaru, Sunbeam, Superformance, Suzuki, Sauber, Saac, Sadler-meyer, Safir, Saker, Samlson, Santini, Sareni, Saturn, Savage, Scg, Schaghticoke, Schick, Scorpion, Scuderia, Sdr Sportscars, Sensor, Serenissima, Serpollet, Shadow, Simbol, Simplex, Sizaire-naudin, Smart, Soleil, Soletta, Spada, Spark, Specter, Spectre, Spice, Spiess, Spitzer Indy, Squire, S.s, Stasis, Stealth, Steeda, Steenstra, Steinmetz, Stillen, Sting, Stoddard-dayton, Stovebolt, Strathcarron, Studie, Styling Garage, Sundoules, Sun-red, Suzusho, Swallow, So-cal, Talbot, Talbot-lago, Techart, Tesla, Toyota, Trident, Triumph, Tvr, Tanner Foust, Tasca, Tatra, Tatum, Technical, Tein, Teverbaugh, Thomas Flyer, Thury-Nussberger, Tiger, Tmg, Tmr, Tojeiro, Tommy, Tom, Toray, Townsend, Trabant, Transstar, Trd, Troutman-Barnes, Tucker, Turbo Technics, Turcat-méry, Turner Motorsports, Tushek, Trion, Tauro Sport, Tramontana, Ultima, Unipower, Valmet, Vandenbrink, Vauxhall, Vds, Vector, Veilside, Vemac, Vencer, Venturi, Veritas, Vgd, Victress, Virago, Vision, Vl-automotive, Voisin, Volkswagen, Volvo, Vörsteiner, Vortex, Vūhl, Wanderer, Wcc, Webb, Weber, Weineck, Welter, Westfield, Wiesmann, Williment, Willys-knight, Yamaha, Yenko, Yes, Zagato, Zender, Zenos, Zenvo, Zytek

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