What is the fastest car in Saints Row 4, and where can I find it?

Solution 1:

The Saints Row Wiki lists the vehicles in the game and sorts according to their maximum speeds, categories, and other statistics.

From that source, the fastest cars are (info in parentheses are how to get them):

• 2-person capacity cars
  • Attrazione
  • Wraith (Shaundi's "Under Pressure" side quest reward)
• 4-person capacity cars
  • Blade
  • Genkimobile ("The Kinzie Gambit" primary quest, "All Hands on Deck" mission reward)
  • Hammer
  • Infuego
  • Pacemaker

If there is no unlock or reward info listed, then that means that the cars are either randomly parked or driven by NPCs. The 'unlockitall' cheat and the Additional Cheats mod (PC only) can also add many of those cars to your garage.

Solution 2:

The fastest vehicles in the game in no particular order are:

• the Wraith,
• an alien vehicle called the Void
• Attrazione

These three vehicle attain the highest speed in the game, with or without nitrous. But personally, I think using the Super Sprint is the fastest way to move around. :)