Yes, they are the same as the 3. I had one installed last week that I bought used from the Mazda 3 forum for about $20.00. I also have one installed in my Mazda 3 for over three years now with no problems. I clean and oil it every six months. They have one million miles warranty on K & N filters.
Year: 2008
Where: Roseville, CA
Trim: Grand Touring
Color: Galaxy Gray
Tranny: Auto
Any extra accessories: Wheel locks & Cargo Net
Price you paid for your Mazda5: $21,400 + tax & fees