SmartFuel can help you find cheap gas nearby or along your route — including at Costco — using Oil Price Information Service data to ensure accurate pricing. Free for iPhone with one-month service. Thereafter, service is $4.99 for six months or $8.99 for one year.
GasBag finds cheap gas and provides a mileage log to track fuel efficiency. Free for iPhone. Ad-free GasBag Pro is 99 cents and can track multiple vehicles.
GasHog tracks your mileage and offers tips to help you go farther on a gallon. For iPhone, 99 cents.
RepairPal uses GPS to locate repair shops, provide ballpark estimates and find roadside service. Shops with sponsored listings usually appear first. Free for iPhone and Android.
Gas Cubby tracks gas and service expenditures and lets you export the data using email. Free (with ads) for iPhone, or $4.99 (ad-free).
On the road
iExit finds food, gas stations and points of interest off the highway exit; lets you filter searches by type of gas, food, etc., and the in-app Google maps guide you there. For iPhone, $1.99.
Waze GPS & Traffic provides real-time traffic updates and turn-by-turn voice navigation to help you avoid gridlock. It quickly guided me around rush-hour traffic, showing me new shortcuts to West Hollywood. Free for iPhone, Android, BlackBerry and Nokia.
INRIX Traffic provides real-time traffic info and forecasts using real-time and historical data. Free for iPhone and Android.
iWrecked Auto Accident Assistant helps you take pictures and record accident info. Free for iPhone.
MyAssist can help you find a dry cleaner, last-minute hotel, flight, rental car, etc., while you're on the road. Free for iPhone, BlackBerry and Android. Five requests are $9.99 a month; 15 and 25 requests are more.
Expedia Hotels helps you book last-minute lodging from the app. Free for iPhone.
Parking in Motion helps you find and reserve parking spaces. It shows rates and provides directions. Free for iPhone.
Line2 provides a second telephone number that works with Wi-Fi, 3G/4G and cellular service for better reception in areas where it is poor. The seven-day trial is free; thereafter service is $9.95 a month (less for longer pre-paid subscriptions). Free for iPhone and Android.
Fone lets you chat or make free phone calls to Facebook friends without revealing your phone number. Free for iPhone (with ads); ad-free Fone Pro is 99 cents.