Consumer Reports magazine has issued its periodic survey of what it and its readers consider the best cars on the market, and not surprisingly the news is not good for the Detroit-centered manufacturers.

But what should the average car buyer glean from the 2007 report?

You’ve probably already seen the headlines: Cars and trucks made by Japan-based manufacturers took top honors in 10 categories of the magazine’s 20 categories:

The Japanese winners were the Honda Fit (budget car), Toyota Rav4 (small sport utility vehicle), Honda Civic (small sedan), Honda Accord (family sedan), Toyota Highlander Hybrid (midsize SUV), Toyota Prius (green car), Mazda MX-5 Miata (fun to drive), Infiniti G35 (upscale sedan), Toyota Sienna (minivan) and Infiniti M35 (luxury sedan).

But here are some things you may not have read, which may affect your shopping decisions:

Not all cars from Japanese manufacturers are great. Despite having two of the best vehicles from its Infiniti division, Nissan also had three vehicles rated subpar by Consumer Reports: the Armada, Titan and Infiniti QX56. The new Toyota Yaris received a thumbs-down rating, despite the overall high marks for Toyota vehicles.

Conversely, Detroit-based manufacturers build some very good vehicles, even if they didn’t break the Top 10. The Ford Fusion, Mercury Milan and Cadillac CTS all got positive nods.

Mercedes-Benz, once the benchmark for value in a car, fell toward the bottom of the magazine’s quality ratings. But does that mean all Benz cars are suspect? Much of the blame for the overall low rating can be placed on the high-volume, entry-level C-Class cars, the ML SUV and glitches with the outgoing S-Class.

Smart shoppers may find more satisfaction buying an older car with high quality ratings than a new vehicle that’s not rated at the top of its category. The most startling example: A 1998 Lexus LS sedan was ranked slightly higher than a 2006 Mercedes-Benz ML500.

But buried in all the “who-won-who-lost” shouting is a nugget of good, sound shopping advice that transcends these annual rankings.

“We think consumers should focus on buying the best car for their needs, no matter who builds it or where it is built,” the magazine wrote.

What that means to consumers is that they should use these rankings as guidelines, but should give more weight to a vehicle’s price, size, fuel economy and a buyer’s personal needs, rather than making a decision based solely on where a vehicle ranks.