You definitely want a Cyclone, as it is by far the fastest vehicle in the game, with a speed stat of 17.
For boosters, I think it's a matter of personal preference. I like using the Heavy Booster (90mph) as I can then throttle exactly how long I want/need the speed. If you're going to be exploring open area where there's low chance of crashing into obstacles (so places like the Draughts on Pandora or Floodmoor Basin on Eden-6), the Sonic Booster (95mph) - which goes faster the longer you use it - can also be very useful. There is also the Firestarter Booster (90mph).
Also use the Stripped Armor to avoid a penalty to acceleration.
An absolute requirement for exploration is the Hover Wheel, which makes your vehicle hover when hitting the e-brake. It allows for insanely good maneuverability.
With this wheel, you can turn a complete 180 degrees almost instantly, plus it lets you get your vehicle into places that the other vehicles simply can't fit because it allows for micro-corrections to your positioning. It's also really great in combat since you can actually attempt to dodge projectiles from enemy attacks.