Kaido to me personally was just too fantasy. The roads look too wide and like..half of the course as insane roller-coaster-like camber corners and another half that's a bit more real. I think it was New Downhill and Old Downhill.
I thought it was just a cluster f...I have played 3 & 4. Physics wise; steering wheel physics are controller are bit complicated avoiding some potential in T.A. Tried getting over 1 min range on Tsukuba with the MiNE'S R34 and got 1 min flat, in GT5; I got like 57 seconds.
The course obivously doesn't exist but Fujimi is in Saitama. Speaking of Kaido, played bit of TXRD2/Kaido Battle 3 and the Touges are awesome in that game. Wouldn't mind having Hakone, Happogahara, Usui, Myogi, Haruna/Akina, Akagi, Hiroshima, Irohazaka, etc. wish Shomaru (because Saitama) was in TXR but G.R.P (Genki Racing Project) was finished.
Really great game despite critic reviews with an arcade-game mind and not a simulator mind because the game's physics were ACTUALLY done by 2 of the famous Japanese Racing drivers. Which are, Manabu "MAX" Orido and Nobuteru "N.O.B./No One Better" Taniguchi xD You might have notice back in the old days (early to mid 2000s) that they had Genki sponsors on their racing suits.