i dont think their is anything new car wise that i am looking forward to. im more intrested in the driving dynamics.. i think forza3 was a very raw fun game... the forza colab with(top gear) is still inm y mind the best forza to date....
i would love to see them design the skins/dynamics for the core 90's jdm cars... supra,rx7,300gtvr4,skyline. maybe give us the top tier of those cars.. the jdm 99 supra, the r1 rx7,the nismo z r34,limited edition vr4,the 98 jdm mr2 hard top. allow for the hard top counterparts of soft top cars... ie mugen s2k,hard top mita,hard top m3 z3 i personally hate the look of the soft tops but the hard tops looks amazing.. and most spec convertable cars run the hard tops for chassis stiffness...
in a the forza's i mentioned above i had really tweekend the nissan s14 for the taskuba circut and had a really good setup that took roughly a month to get where i wanted it.. car was on rails.. so i guess that is a car id like to have. possibly the kouki version not the zenki... but like most driving games i enjoy the s class the most. production cars that are under dogs against the low level super cars with a few mods becomes great racing.
id also like to see spec racing.. like spec mita series, ferrari 355 competition spec racing. non modable cars that you can race as a seies make it a group/skill ai based matching system.. say 20 cars per group with advancment... i thnk would change how forza/driving games work.