Q: I am considering buying a 2010 Prius. Would I do better, money-wise, to buy a cheaper five-door car, like a Mazda? I drive 20,000 miles per year. What do you think?

Katie Kool, Fort Collins, Colo.

A: It depends on how you define “ long run. ” The Prius uses about $500 less fuel annually than the Mazda3, according to EPA estimates. When comparing Prius and Mazda3 models with similar trim levels, it takes five to 10 years to “ break even ” from fuel savings. If you buy the least-expensive Prius model instead of the most expensive versions of the Mazda, you start saving almost immediately.

But saving fuel, not money, is the point of buying a Prius. If paying a few thousand dollars extra to get 50 miles per gallon instead of 30 doesn't thrill you, you'll be better off with the Mazda. Or you could buy a 20-year-old Honda CRX HF, which topped 50 mpg without the complication of hybrid power.

Q: My two-year-old Hyundai Azera recently needed its second battery replaced after two years one month and 12,220 miles. I replaced the first battery after one year and 6,000 miles. The dealer told me this is normal because of the hot weather in this area — which has recently reached 110 degrees. Is this true?

Detlef Eymer, Rancho Mirage, Calif.

A: High temperatures can hurt car batteries, but you shouldn ’ t have to replace them every year. Try attaching an automatic charger — also called a trickle or float charger — to your battery when you aren ’ t using the car. They use a variable charging rate to fully charge the battery and then keep it from deteriorating by maintaining a proper charge level.

Since you have been driving it about 6,000 miles a year, there are probably times when your car sits unused for extended periods. Your driving patterns also may not be ideal for keeping the battery fully charged. Charging between trips may solve the problem.

Q: After a nine-month layoff, I recently found a job in Boulder, Colo. It involves a 50-mile commute each way. I am looking for a reliable, fuel-efficient car that can handle snow and befits a senior legal executive.

S. Shea, Littleton, Colo.

A: The Audi A4 comes to mind. I prefer the wagon to the sedan, but either will help you look sharp arriving at meetings. Its all-wheel-drive handles slippery roads well and the turbocharged four-cylinder engine is easy on fuel while generating enough power to keep the driving fun.

Q: After 115,000 miles and 6 ½ years, it is time to replace my 2003 Honda Pilot. We are looking at a slew of new sport-utility vehicles and crossovers. We need seating for at least seven and some rear storage space when all the seats are in use. Except for the Toyota Highlander Hybrid, there doesn't seem to be much difference in fuel economy.

Kara Haire, Annapolis, Md.

A: Only a handful of crossovers are really big enough to handle seven passengers comfortably, unless at least two are infants. The Ford Flex and Chevrolet Traverse are my favorites because their interiors are huge while their exterior footprints remain manageable. The Highlander hybrid ’ s fuel economy is especially good for a three-row crossover, but it lacks the others ’ cargo space.