Heat oven to 350℉/177℃.
Spray three 8-inch round pans with baking spray. Set aside.
In a medium bowl, sift together flour, baking powder, and ¾ cup sugar.
Whisk in lemon zest. Set aside.
Using an electric mixer, beat egg whites, ⅓ cup sugar, and cream of tartar to medium peaks. Set aside.
In a large bowl, whisk together egg yolks, vegetable oil, water, and vanilla.
Stir in flour, a little at a time.
Fold in meringue in three additions.
Divide evenly among prepared pans.
Bake for 15-20 minutes, until cake tests done.
Turn out and allow to cool.