The Hirohata Merc is a 1950s custom car, "the most famous custom of the classic era". Setting a style and an attitude, it had a "momentous effect" on custom car builders, appeared in several magazines at the time and has reappeared numerous times since, earning an honorable mention on Rod & Custom's "Twenty Best of All Time" list in 1991. The impact may be measured by the fact that, after more than fifty years and numerous owners, it is still known as "the Hirohata Merc".
Constructed in 1953 for Bob Hirohata,  it was designed and built by George and Sam Barris, assisted by Frank Sonzogni. It started out as a 1951 Club Coupe. Nosed, decked, and shaved, the top was chopped four inches in front and seven inches in back, and the vertical B-pillar was reshaped so that it curved forward. The rear window had its posts removed, and was raked steeply forward, requiring a new roof piece to be fabricated. Side trim was replaced with that from a 1952 Buick (the spears), augmented by grille teeth from a 1952 Chevrolet (three per side) and functional scoops. The front wheels are fitted with traditional sombrero ('47-'51 Cadillac) hubcaps.
Barris used a vee-butted windshield, a very common customizers' trick in that era, rather than a one-piece windshield, which was available on the '53 Merc. He added Appleton spotlights, frenched the headlights (which were fitted with '52 Ford rings), and added '52 Lincoln Capri taillights. The exhaust pipes were routed out through the rear bumper, beneath the taillights, and a pair of radio antennae were frenched into the rear quarter panels.
The Hirohata Merc was painted in two shades of green, a total of thirty coats, which were applied by Junior Conway. The interior was upholstered with tuck-and-rolled naugahyde. The dash, seats, and headliner were white with dark green inserts, matching the exterior lower body color (below the Buick spears).
Hirohata later replaced the original Mercury flathead engine with a transplanted Cadillac engine, creating the nickname "Mercillac" ("merk-ill-ack"), in the fashion of rodders of the period, who in the same way created Fordillacs and Studillacs.
Hirohata sold the Merc, and the car changed hands several times. It was eventually purchased by Jim McNiel, who used it as a daily driver for years, then placed it into storage. Ultimately, McNiel restored the Merc to her original configuration. The paint was done by Hershel "Junior" Conway at Junior's House of Color.
- Hot Rod March 1953
- Motor Trend March 1953
- Rod & Custom October 1953
- Trend Book 109 Custom Cars 1954 Annual
- Rodding and Re-styling January 1956
- Trend Book 143 Restyle Your Car
- Rod & Custom August 1989
- Road & Track August 2004
- Trend Book 133 Custom Cars 1957 Annua
- The Big Book of Barris
- Favorite 50 Rods & Customs, Rod & Custom, December 01, 2003
- Rod & Custom, 8/89, p.12.
- DeWitt, John. Cool cars, high art: the rise of kustom kulture, University Press of Mississippi, 2001. ISBN 978-1578064021 , p.69.
- DeWitt, p.70
- DeWitt, p.80
- Rod & Custom, 8/89, pp.12 & 14.
- Hoving, Rik. "'50s Hirohata Merc Photo's album - including article from Rod & Custom October 1953". FOTKI INC.
- Jalopy Journal.
- Street Rodder, 1/85, p.111.
- The same body style as D'Agostino's Merc. Street Rodder, 1/85, pp.52-3.
- Hirohata, Bob (2004). "Kross Kountry in a Kustom". In Leah Noel. Rod and Custom in the 1950s. Motorbooks International. p. 29. ISBN 0760316309.
- Barris.com Visible in the photo.
- Barris.com Visible in the photo
- They are identical to those used on D'Agostino's Merc. Street Rodder, 1/85, pp.52-3.
- DeWitt, p.72.
- DeWitt, p.69
- Rod & Custom Magazine, 8/89, p.12.