Related Clues:

• EU auto requirement since 2007
• Workout "washboards"
• They look best when ripped
• Toning targets, for short
• Muscles that may be sculpted, informally
• They're strong when ripped
• Planks work them
• Washboard from working out
• Flat 'six-pack'
• Core components
• Core muscle group, briefly
• Crunch target
• The pack in a six-pack
• 'Rock-hard' muscles
• Many admire ripped ones