During the summer, I took a 32 day road trip from Chicago to California and back. This trip covered 6,717 miles. My Prius achieved an overall gas mileage of 53.7 mpg for the trip. That means, I burned 125 gallons of gas over that month of driving.
On average, I paid $2.15 per gallon. Today, gas is even cheaper! So, my final gas bill came to $268.00, or just $8.37 per day, for the entire trip. Some of the hotels in Los Angeles and San Diego cost nearly that much for a night. With the Prius economy and lower gas prices in general, the cost of gasoline is no longer a major expense--even for trips that cover thousands of miles over several weeks.
Here's photo of the Prius in camping mode at Joshua Tree National Park in California. Prius camping places me in the most ideal locations for photography at the lowest possible cost.