For the Desoto uninformed, the Firesweep was the least expensive of the 4 lines available, top dog being the Adventurer which brings serious 6 figure cash, not that the topic car is exactly cheap.
1958 FIRESWEEP SERIES LS1-L (8-Cylinder wedge-head V-8): This series continued to use the Dodge chassis. Body side trim was redesigned so that the upper molding ran at an angle to the upper corner of the tailfin. There were "Firesweep" rear fender nameplates, and a continuous band of metal decorated the front lip of the hood and climbed over the headlamp hoods. Firesweep Sportsman models had the dome-like windshield seen on 1957 convertibles, while sedans continued with a visored windshield header. An upgraded interior, matching those in the Firedome could be had in selected Firesweep models at extra cost., Electric windshield wipers were employed and the new "B" Series 350 CID V-8 wedge engine was fitted. A Power Pack 4-barrel carburetor option was available.
1958 FIREDOME SERIES LS2-M (8-Cylinder wedge-head V-8): The Firedome was basically unchanged for 1958. "Firedome" nameplates were placed on the rear fenders. All Firedome models had the same side trim as the lower priced Firesweeps, but the front molding treatment was different. "Windsplit" ornaments for tops of front fenders were an option. The interior was upgraded over the Firesweep. Upholstery materials were defined as "Frontier Homespun" fabric (cowboys were a big thing in 1958) in combination with grained vinyl, all colored to harmonize with exterior finish. Firedomes used the new "B" series V-8 but with an increased displacement to 361 CID.
1958 FIREFLITE SERIES LS3-H (8-Cylinder wedge-head V-8): The top rung DeSoto series was identified by "Fireflite" rear fender nameplates and a distinctive upper body side molding which extended the full length of the car and incorporated special medallions on sides of front fenders. "Windsplit" fender-top ornaments were standard equipment. "Color Sweep" trim was standard on hardtops and convertibles. Fireflite interiors were a step up from the Firedome and leather was an option on some models. The Fireflites used the same new "B" series 361 CID V-8 as the Firedome, but fitted with a 4-barrel carburetor. A springtime trim package was released as an option for all models except Adventurers, and featured two groups of four vertical bright metal deck lid slashes affixed one group to each side of the recessed license plate housing. New exterior colors were announced about the same time. Fireflite interiors were done in metallic Damask and vinyl and incorporated integrated arm rests with aluminum finish recesses above.
1958 ADVENTURER SERIES LS3-S (8-Cylinder wedge-head V-8): The Adventurer models were still a Fireflite subseries, but pure performance and luxury. Like the Fireflites, these high-performance cars came standard with Torqueflite transmission, backup lamps and full wheel covers, but there were some other extras that were standard: power brakes, dual exhausts, dual rear radio antenna, dual outside rear view mirrors, white sidewall tires, dashboard safety panel and special paint and trim. The latter included gold highlight surrounds, twin groupings of four deck lid bars, triangular rear side sweep inserts and special upholstery. The Adventurer also used the same new "B" series 361 CID V-8, but was fitted with dual 4-barrel carburetors, and a camshaft upgrade but no cylinder head/valve increases over the Fireflight. It was rated at 345 HP. A radical new option was an electronic fuel injection system manufactured by Bendix which increased the output to 355 HP. Cars with fuel injection had special nameplates above the front fender medallions. Most were later recalled to the factory and converted back to Adventurer "standard" dual-quad carburetors due to the fuel injection system's unreliability.
