Sure, you can buy it. But can you afford to drive it?

Anyone who has ever shopped for a new vehicle knows the drill: Compare offers, work down from the sticker price, and don't be beguiled by the sales patter. But before you buy your next car, consider the long-term equation: How much do you want to spend on vehicles in your driving lifetime? The minimum? The average? Is it more important to save a few dollars or have the right car?

These long-term questions are important because, depending on what they drive, Americans typically will spend at least $240,000 to $350,000 each for the privilege of driving for 50 years, according to the American Institute for Economic Research (AIER) in Great Barrington, Mass.

Put another way: If you're like most Americans, you spend much more each year on your car than you contribute to a retirement plan, or spend on healthcare or education.

Granted, most people don't think long-term when they go car shopping.

"The act of buying a car is all about that new-car smell, that great-sounding stereo, the excitement," says James Bell, publisher of IntelliChoice magazine, which tracks automotive costs and values.

That's understandable, says Mr. Bell. But getting a handle on the full financial outlay associated with ownership - insurance, depreciation, maintenance - can help steer buyers around some long-term financial potholes.

For a start, some types of cars are cheaper to buy and operate than others. If you stick with small sedans during your lifetime - think Honda Civic or Chevrolet Cobalt - and hold on to each one for 12 years, you'll pay on average just over $4,800 a year or $240,704 over 50 years, according to AIER.But drive large sedans - a Mercury Grand Marquis or Toyota Avalon, for example - and under the same assumptions you'll shell out an average of $7,000 annually or $349,968 over 50 years. SUV and passenger van costs fall somewhere in-between. (See chart, page 16.) But the cheapest car isn't always the least expensive over the long term, experts warn. When you buy - and even how you finance the purchase - can make a big difference.

"Because of the way financing programs are going now, being extended by six, seven, even eight years, and [with] zero percent financing, and rebates, people - especially young, first-time buyers - are putting themselves into really bad economic cycles," Bell says. They're taking on too much debt and stretching payments into a period when depreciation and wear leave them with little equity in their vehicles.

Add to that the stealth costs. Operating a new car - independent of payments - cost Americans an average of $8,431 last year, according to the American Automobile Association (AAA), which expects to release a 2005 figure soon. That's up from less than $6,000 in 1994.

AAA's annual estimates run higher than AIER's ownership calculations because most consumers don't hold onto cars for 12 years. Nevertheless, the longevity of cars is creeping up.

"Cars are on the road for longer periods of time now than they used to be, and that's good news for consumers," says Jack Gillis, director of public affairs at the Consumer Federation of America (CFA). Even the fairly dramatic repair costs associated with older cars should be viewed in context.

"What consumers need to do once they absorb the shock of those big expenses is take a look at what the payments are on a new car," Mr. Gillis says. Though he says many people get the urge to buy a car every seven years or so - one reason cars per household began outnumbering licensed drivers in 2003 - that cost analysis might keep them in their vehicles a bit longer.

"The tradeoff is that you don't necessary have the latest in technology and you don't necessarily have the latest in safety," he adds.

Some of those advances are considerable. For example, stability control, reportedly now available in about 20 percent of new vehicles, can vastly improve handling. Others are niceties that improve the driving experience. Longtime drivers who would never bother to improve on their stock audio system might be stunned by the offerings on satellite radio, now available in some cars.

The 2005 Acura RL has been called a "$50,000 computer on wheels" for such features as a real-time traffic-information system linked to GPS and sun-sensing climate control.

Such new cars also can offer invaluable peace of mind. "But you definitely will have a more economical car the longer you keep it," says Gillis.

Another guideline: Cheap new wheels are not necessarily a passport to low ownership costs.

"That is why the Lexus LS 430 does very well in our analysis," Bell says. "It is not inexpensive to buy, but is it is an exceptional value to own." Other cars on the IntelliChoice list (available in full at intellichoice.com): Honda Odyssey (both LX and EX) and the Chevrolet Silverado 1500 Crew Cab LS 2WD.

But it's not easy finding that low-priced "wonder car" - one that will run forever with minimum fuel and repair costs, not raise red flags with insurers, and age gracefully enough to retain some resale value.

"A lot of people don't achieve that," says Kerry Lynch, director of research at AIER. The institute publishes a $6 booklet - available at www.aier.org - with tables showing how used cars have held their value going back to 1997 models. And, she adds, there are variations on that ideal.

"When you're buying a new car, you want to obviously look for a car that's going to hold its value," Ms. Lynch says. "On the other hand, if you're looking at used cars, we suggest you first look at Consumer Reports and see which cars they recommend mechanically - the ones that stand up well," she says, "and then consider ones that may be a bargain because they have not held their value very well."

A failure to hold value doesn't necessarily reflect poor reliability, she adds. "So in a sense you get a better deal, if you're not at that point concerned about the resale value." Others say buying even a new car based on its perceived resale value is a risky tactic.

"It's really difficult to predict actual resale value because of a whole variety of factors," says the CFA's Gillis, also the longtime author of an annual buyers' guide called "The Car Book" ($20 at www.autosafety.org).

"There could be a run on a particular car that increases its new-car value, which causes the used-car value of that particular car to inflate," he says. Or "it could be that suddenly a car gets a bad reputation for something [and] there's a lot of bad PR," deflating the market value.

Gillis, Bell, and others support the widely hailed practice of buying good used cars in order to allow a first owner to absorb the initial depreciation.

"Generally, if you look at the depreciation cycle, especially with the rebates and the incentives, that first 18 months is where the majority of the depreciation hits," says Bell. "And then it starts to average out a bit. But each vehicle has a very different curve."

Not that it's always bad to be the first on your block to own something new, even fundamentally new.

AIER's Lynch still sees gas-electric hybrids, for example, as something of a financial gamble - although tax incentives to buy them might tip that balance.

But during a telephone interview, Bell is creeping through Los Angeles traffic in a 2004 Toyota Prius, running "like a golf cart," he says, while all the cars around him burn gas. Some people have told him he might might face costly battery-replacement issues down the road.

"But there's a warranty on the system," he adds, because Toyota - like many carmakers - aims to maintain its reputation.

Most manufacturers know about that intangible: To keep customers loyal, the benefits of ownership over time must equal or exceed what the customer paid.

When considering the costs associated with buying a car, consumers should weigh a variety of factors besides price, monthly payments, and resale value. Here are some other prepurchase steps experts recommend you take to keep ownership costs low:

• Check insurance costs. The best way to know whether one model costs more to cover than another is to call your carrier for a quote, with year and model in hand. Shop for better deals every few years, and ask about discounts.

• Price out your fuel economy. Having a miles-per-gallon number is useful, but it won't become real until you estimate your annual mileage in city and highway conditions and calculate a dollar cost per year.

• Consider repair costs. After a car's warranty expires, consumers are likely to experience repairs such as replacing brake pads and shock absorbers. "The differences among the cars to replace them if they should fail is quite remarkable.... And knowing that before you buy can save you money down the road," says Jack Gillis, whose annual buyer's guide, "The Car Book," lists the costs of nine typical repairs for a variety of models.

• Weigh that warranty. Check the cost of preventive maintenance required by the manufacturer to keep the warranty active; it could run from $0 to $15,000 for the first 50,000 miles, says Mr. Gillis.

• Question marquee mythology. As shown by the rising reputations of several American makers including General Motors, and of South Korean carmakers Kia and Daewoo, automakers can make great strides, fairly quickly. (One barometer, technical service bulletins, can be found at sites including www.nhtsa.gov.)