Gas prices are nearing a four-year high nationally, with the average US gasoline price reported to be over $4.50. Prices have surged in recent days, with some areas seeing costs exceed $5 a gallon, and the increase is attributed to various factors, possibly including a fuel crunch and conflict. The rising prices have resulted in higher costs to fill up vehicles, with some reports indicating it now costs $160 to fill up a top-selling vehicle.