Assuming we do the any% route first:

Tips: for faster loading times, exit back to menus instead of driving to City Transport or garage whenever you change cities or vehicles for restricted races if you already prepared them.

Start with the Dodge SRT-4 ($21,450). Complete the initial race, then do Vanessa and Bishop (skip Carlos for now), with the City Tournament for the Lexus IS300 being done in between. Upgrade the D-Class Tuner to level 1, then defeat Phil. Vanessa will later return for a rematch, defeat her.

Then open Atlanta, beat the following racers: Dre -> Cheng -> Roy -> Lamont -> Roy II . Buy the 1998 Toyota Supra by selling the Class D Tuner (SRT-4 or IS 300) then upgrade it to level 1 after unlocking said upgrades for Class C. Skip Vito and Naomi, we will just revisit them post-US Champs.

When Detroit is open: Upgrade the Supra to level 2 and Defeat all Detroit Racers, in the following order: Spider -> Kioshi -> Roy III -> Angel -> Leo -> Ceasar I -> Ceasar II. Most likely at this point, you are pretty much guaranteed to be able to obtain the quad-nitro McLaren F1 LM. Use the Supra for all of Detroit, then sell it and the Hotmatch Cuevito and you will be able to afford the F1 and the level 2 nitrous. You will be unable to afford them until you beat all 7 racers in Detroit.

Start the U.S. Champions route by beating Detroit racers (Roy, Kioshi, Ceasar)

Proceed to Atlanta (Angel, Lamont)

Then finish the Champion series in San Diego (Spider, Vanessa)

Now for the rest of the Career 100

Start the SD Cleanups portion (Do the SL55 tournament first if you beat Vanessa last, then with the F1, use it to do cleanups (including 300C tournament and Carlos (+Bel Air tournament), plus the 7 By Invitation Only races.

Proceed later to Detroit and do the Bad Boyz Tournament and City Tournament, as well as the four By Invitation Only races. Do whatever is nearer to Vince's garage.

And later head back to Atlanta for the ATL cleanups (Exotic club races, Escalade EXT tournament, Vito, Naomi, SS1000 tournament, 5 BIO club races, and now you have earned that Chrysler ME Four Twelve).

With all exotic-eligible races now done, now, buy the Club-specific vehicles and max upgrade them.

Recommended vehicles are:

Tuner: SR, Viper GTS-R (fastest in B-Class) or Supra.

Muscle: Any Class B (the best option is the 1981 Chevrolet Camaro)

SUV: Gemballa GT750

Sport Bike: Aprilia Mille Factory or Ducati 999R (Factory has better performance and cheaper)

Chopper: Hotmatch D'Elegance (though any B-Class chopper works)

For Luxury, use the Mercedes SL55 you won from the tournament earlier.

Do all club races, in any order, the Career ends when you win the Cadillac Sixteen.

Tokyo:

Do the By Invitation Only tournament for the '98 Gemballa F355, then do 34 purple races, and do the Imperial Palace Tournament when it opens. Chrysler ME Four Twelve or McLaren F1 LM recommended.

For each Tokyo tournament, use the following vehicles:

By Invitation Only/Imperial Palace (A): McLaren F1 LM or Chrysler ME Four Twelve

Unbeatable Street Racers/Asakusa (C): Nissan Skyline GT-R R34.

American Royalty: Use whatever B-Class muscle you used for the American Royalty.

Chopper: Use whatever you used for Chopper of America.

Luxury Rollers/Wharf: Mercedes SL55 AMG

Ginza: Chrysler 300C, Infiniti G35 (have to go to garage and upgrade it) or buy Cadillac CTS-V

Original Riders: Aprilia Mille Factory.

Big Playas: Gemballa GT750.

Run ends when you have won the Cadillac Sixteen and unlocked the Tokyo Police Car. You will most likely end up getting reimbursed the cash value for at least one of the Tokyo Challenge prize vehicles but will still unlock it.