Web sites that compare gas prices at different stations have been around for years, but the offerings are becoming more sophisticated. In addition to gas prices delivered to cellphones, some Web sites now offer fuel consumption calculators, scout out sources of alternative fuels and even explore mass-transit options.

For some, technology helps them get more mileage out of their money. Gasoline prices are up 16% so far this year, to $3.61 last week, or about 18% higher than this time last year. Analysts are suggesting the price could hit $4 before the summer driving season is over.