The Week in Review lays out future Specialty Dealer sets into September. Based on the end of the list it looks like the 12 weeks will repeat indefinitely.
www.forzamotorsport.net/news/wir_7_5_19Specialty Dealer
The following cars will cycle through the Specialty Dealer:
Week 1
1970 Datsun 510
1971 Lotus Elan Sprint
1967 Lamborghini Miura P400
1960 Aston Martin DB4 GT Zagato
Week 2
1957 Maserati 300 S
1956 Lotus Eleven
1957 Ferrari 250 Testa Rossa
1956 Jaguar D-Type
Week 3
1965 Alfa Romeo Giulia Sprint GTA Stradale
2015 Volvo V60 Polestar
2015 Jaguar XE-S
1987 Nissan Skyline GTS-R V-Spec
Week 4
1968 Lancia Fulvia Coupe Rallye 1.6 HF
1979 Opel Kadett C GT/E
1973 Ford Capri RS3100
1971 Nissan Skyline 2000GT-R
Week 5
1977 AMC Pacer X
2013 Hyundai Veloster Turbo
1986 Dodge Shelby Omni GLHS
2011 Audi RS 3 Sportback
Week 6
2009 Peugot #9 Peugot Sport Total 908
2015 Ford #02 Chip Ganassi Racing Tiley Mk XXVI Daytona Prototype
2017 Porsche #2 Porsche Team 919 Hybrid
2014 Audi #4 Audi Team Joest R18 e-tron quattro
Week 7
1981 Ford #2 Zakspeed Racing Capri Turbo
1995 Chevrolet Corvette ZR-1
2017 Renault R.S.17
1960 Porsche 718 RS 60
Week 8
1960 Chevrolet Corvette
1968 Opel GT
1970 International Scout 800A
1970 Alfa Romeo Montreal
Week 9
1969 Ford Mustang Boss 302
1967 Eagle-Westlake T1G
2016 Dodge Viper ACR
2009 Chevrolet Corvette ZR1
Week 10
1999 BMW #15 BMW Motorsport V12 LMR
1965 Pontiac GTO
1993 McLaren F1
1966 Chevrolet Nova Super Sport
Week 11
1991 Mazda #18 Mazdaspeed 787B
1991 Nissan #23 Nissan R91CP
1989 Mercedes-Benz #63 Team Sauber Mercedes C9
1998 Ferrari #30 MOMO Doran Racing F333
Week 12 (Begin again with Week 1)
1963 Ferrari 250LM
1965 Shelby Cobra Daytona Coupe
1961 Maserati Tipo 61 Birdcage
1968 Alfa Romeo 33 Stradale