This worked for me.

I met my girlfriend a year and a half ago, at which point I'd been carless for 4 years. (At the time, I had a motorcycle, but no bicycle.) When we were planning our first date, I felt self-conscious about my lack of a car and needing her to pick me up. So I explained to her that I was doing without a car in order to better save towards a condo downpayment. That was sort of true -- I was indeed saving towards a condo down payment, but that wasn't the main reason I was carless. The "saving for a condo" explanation was a way for me to express to her that despite my lack of a car, I was financially responsible and stable. If anything, my explanation probably won more points with her than owning a car would have.

I bought the condo a year ago, have taken up bicycling and reduced the motorcycling, and am no closer to getting a car*. And she's fine with that.

* Well, I am starting to toy with the idea of getting a small pickup that I could use to haul around a dirt bike or track bike, as well as bicycles, kayaks, etc.