DEAL: $10 — regularly $30. You save $20.
This combo discounts both items, not just one. You get a full Tiki Wash plus the Basic Express Interior add-on, and both are marked down.
What you get, and what it normally costs:

Tiki Wash — $15 value
Basic Express Interior — $10 value (this is the add-on offered on most washes)

Tiki Wash includes:

Machine Wash
Soft Cloth Wash
Wheel & Tire Cleaner
Spot Free Rinse
Hand Dry
Sealer Wax
Bug Remover
Tire Shine

Basic Express Interior includes:

Interior Vacuumed
Windows and Dash Cleaned
Door Jams Wiped

Free high-powered vacuums are included with every wash.