This week over at Streetsblog L.A. our “Why You Ride (or Don’t)” survey series became the center of a heated discussion when the blog proposed that respondents who drive are likely underestimating their monthly transportation costs (perhaps in part due to the way we asked the question).

In our “Why You Don’t Ride” survey we asked non-transit riders (in other words, drivers), “On average, what do you spend each month on transportation? (Including gasoline, maintenance, parking, tolls, insurance, etc.)”

We gave respondents four choices:

• Less than $50
• $50 – $100
• $100 – $300
• $300 – $500
• More than $500

Here’s a look at the answers we’ve received:

As you can see, the majority said they spend $100-$300 each month, and only a minority report spending more than that. Do these numbers seem realistic when you include all the many costs of car ownership?

I imagine most of our readers have a pretty good idea of what their cars cost them, but don’t include every fixed cost when it comes to calculating their monthly transportation expenses because, frankly, they don’t foresee themselves giving up their cars anytime soon.

Here’s how one commenter on Streetsblog put it:

“The key here is that once you have made the decision to own a car, it makes sense to get as much benefit out of it as you can by forgoing the expense of a transit pass and avoiding the waste of time that comes from taking transit. If you really want people to commute by public transit then the focus needs to be on making the places where people live and shop pedestrian friendly enough that going without a car is not a significant sacrifice. If you don’t do this then transit is competing against the (low) marginal cost of owning a car rather than the full cost of owning a car.”

For comparison’s sake, let’s take a look at how transit riders responded to the same question in our “Why You Ride” survey:

The results of our surveys seem to say that even though non-transit riders don’t report spending huge sums of money each month on transportation, they definitely seem to spend more overall than those who ride transit. By the way: 61% of respondents who take transit also reported owning a car.