Pac-Man mode :
Race more than 3,000 kilometers in total distance to unlock the Pac-Man mode.

99 lap mode :
Beat the top score in each race of the Time Attack GP in Extra Mode.

Onscreen display :
Hold Select while racing in third person perspective to get misc. onscreen info.

Intro sequence graphical effects :
If you press R1 during a portion of the intro sequence you will cycle through three different graphical effects, black&white, yellow tint and a blur effect. press L1 one to cycle back again.

Unlock Duel Mode :
To unlock duel mode you will have to place first in all the time trials.

Unlock Hidden Cars :
To unlock these hidden cars you will have to already have the duel mode. If you already have that then go to the EXTRA Time Trails and then look at the records and you will see that not all of them will have NAMCO as the #1 record holder and all the ones that don't have that they will have a different name some of them are Pluto, Angel, Devil, and there's one more car but I forgot the name. After you see those records go and race those time trials and get first in both Lap Time and Total Time it doesn't have to be in the same run. After you do that go to the Duel race and you will see that there are four names and you will have to beat them to unlock a new car, also there will be a Battle Royal after you beat all four of them.

Bonus cars :
Finish the following races in 1st place to unlock the cars in Free run, Time attack and Duel mode:

Rivelta Crinale race - Unlock Devil Drift
Danver Spectra race - Unlock 50's Super Drift Caddy
Kamata Angelus race - Unlock McLaren F1 clone :
Solort Rumeur race - Unlock VW Beetle