To convince her that it's possible, negotiate a time frame with her. "If we can leave the second car parked for one month (or six months, or whatever time period she agrees to), we will sell it."

Accentuate the positive. Calculate exactly how much money will actually be saved on a monthly, yearly and five year basis. Talk up all the great things you guys can do with all that money.

Remind her that you're getting to the age when a lot of men have heart attacks. the exercis you get riding will help reduce your risks.

Just honestly tell her that this is something that will make you happy. I'm sure that your hapiness is important to her, so this is something that might sway her.