Do you really need a new car?

New-car envy. It can creep up anytime. It may snag you at a stoplight when a muscle car or luxury sedan sidles up. Or maybe when the gleaming SUV parked next to you makes the dents in your jalopy all the more obvious.

Get over it.

It’s all too easy to go for the quick fix and trot down to a dealership with checkbook in hand. That might cure your automotive longing—at least until the payments start. But if you calculate your actual costs, buying a new car might be a lousy financial move.

The car you’re driving right now may be a keeper—dings and all. Here’s why: Cars built in the past decade are more reliable than ever. Although the average age of all cars on the road is 11 years, many newer cars will provide trouble-free service for 200,000 miles or more with care.

If your car is only a few years old, hanging on to it will not only free you from a new cycle of monthly payments but also save a bundle in insurance, taxes, and other expenses­—primarily depreciation.

It may be hard to get your head around the idea that shiny new sheet metal is a depreciating asset, but today’s new cars lose 46 percent of their value, on average, in the first three years.

Historically, a draw for a new car is improved fuel economy. But recent low gasoline prices blunt that impact, and even at higher fuel prices, you need to save a lot of money at the pump to make up for those depreciation and sales-tax hits.

There’s one big downside to all of that: Your current ride probably doesn’t have the latest safety and convenience features, and your warranty has probably expired. And no matter how well your car is treating you, even the most reliable models grow more troublesome as they age, as our subscriber surveys have found.

So should you hang on to your old wheels? It depends on a lot of factors, including the condition of your car and your finances. Think about cost, safety, and connectivity. If your mechanic is spending more time with your car than you do and your repair bills are close to new-car payments, it’s probably time to trade up. Or your car may run well, but rust or collision damage can make it structurally unsound. The only older cars worth keeping are the ones that are reliable and safe.

At a minimum, an older car should have electronic stability control and curtain air bags. Both are lifesavers.

Going with a new car is the best way to get the latest electronic safety gear, such as forward-collision and lane-departure warning systems, as well as features like a blind-spot warning system and a rear backup camera. And only the newest vehicles excel in the latest difficult insurance-industry crash tests.

If you’re looking for the latest electronic convenience and entertainment systems, you’re probably going to want a new car. Some features, such as Bluetooth capability for hands-free calls, can be added to an older car with aftermarket equipment but may lack the integration and ease of use of a factory system. Our look at new-car infotainment systems begins on page 28.

Don’t have the cash for a new car? Buy something almost new. You’ll get some of those desirable new features without spending as much. Just be sure to choose from our list of reliable used cars.

Still can’t make up your mind? Check out our decision tree below.

How much a car with higher mpg will save you

Find the intersection of the fuel economy from your current car with that of the ones you’re considering for potential costs savings per year. For example, If you go from 26 mpg to 34 mpg, you save $239. If you want to trade in for a sportier, less fuel-efficient car, the numbers in red show your added fuel cost.

How much it costs to repair your current car

If your annual repair bills exceed a year’s worth of car payments, then it’s time to start shopping. But even dropping an occasional $1,000 bill to keep an older car running might save you money over buying a new car.

How much value that new car will lose

Cars depreciate significantly over the first few years of ownership, often more rapidly than your monthly payments are paying down the loan—putting you “upside down” financially. The chart below shows typical vehicle depreciation based on the average new-car price.