The Surface Transportation Policy Project released a report, Driven to Spend, which compares costs in 25 metropolitan areas for household transportation. One unsurprising finding is that in metropolitan areas with good public/regional transit networks, households spend a smaller percentage of their income on transportation. These metropolitan areas are also less exposed to fluctuations in gas prices through the transportation spending habits of their residents.

"If Baltimore households spent the national average on transportation, (19.1% instead of 14%), they would have spent an extra $2 billion in 2003 on transportation, and if Houston households would have spent the national average on transportation (19.1% instead of 20.9%), they would have saved $1.2 billion on transportation."