Related Clues:

• Natter
• Something that is neither solid not liquid
• (American) petrol
• 16 (US)
• Carbon dioxide, say
• Ethane, e.g
• Solid alternative
• Utility bill item
• Fastball, in baseball slang
• It's a driving concern
• Stuff you pump
• Jeff Gordon goes nowhere without it
• "Juice" for Jeff Gordon
• Car's need
• Ozone, e.g