So you’ve begun planning for retirement and maybe even set an estimated budget. You’ll need to factor in housing and medical care costs and, fingers crossed, money for travel plans. But before you congratulate yourself, ask one more question: Have you considered your transportation costs- either driving your own car or using car services? More generally, have you thought about the place of transportation in your future plans?

It turns out transportation is the second largest cost in retirement after housing. Since 70% of those over 50 still rely on a car for transport, that means there’s car maintenance, insurance, gas, and other associated costs, let alone the costs of purchasing a new vehicle (and click here to read the latest Consumer Reports guide for the best new cars for seniors). And along with driving there comes the inevitable question of when, if ever, an older person needs to stop driving due to physical or cognitive incapacity, not to mention how senior driving is regulated in each state.

But statistics also show that one out five people over 65 don’t drive. They either rely on public transport, private car services or the goodwill of others to take them where they need to go- or they don’t leave the house. And that’s a problematic solution to an ever growing problem. For many, the costs of private transport, or such ride-sharing services as Uber or Lyft, are not financially possible. While companies like GreatCall are making it easier for seniors to gain access to ride shares, that’s a patchwork solution to a transportation problem with real implications for older and disabled people. Many seniors never make it to the doctor because they have no way to get there. And relying on others to drive you means you’re probably only asking for rides absolutely essential, rather than for social or pleasurable reasons. That may lead to the social isolation of seniors. So what’s the answer to this transportation conundrum? Buckle up, because the path to a solution seems bumpy at best.