Related Clues:

• It's mostly nitrogen
• Travel method
• Brake's neighbor
• Epitome of lightness
• ''Fully loaded'' cars have it
• Neon or freon
• Every breath you take
• Electric's partner
• Laughing, for one
• Mustangs go nowhere without it
• It's often stepped on
• It's pumped
• If you're in a hurry, step on this
• Luxury car standard feature
• Tune