Car companies cut their ad spending by 10 percent, to $6.1 billion, through the first half of the year, according to Nielsen’s ad tracking service. That confirms anecdotal evidence media companies have been offering up throughout the year, and it means that the numbers for the second half of the year–when the economy really collapsed–are going to be brutal.

Which goes a long way toward explaining why everyone–from Time Warner’s Time Inc. (TWX) to GE’s (GE) NBC to every Web start-up you can think of–is looking at dwindling ad revenue for the foreseeable future.

And yes, you can point your finger most accusingly at Detroit, if that makes you feel better: While some imports, like Toyota (TM) and Honda (HMC), actually kept spending steady or increased it, the formerly Big 3 all made big cuts. General Motors (GM), the country’s biggest auto ad buyer, dropped spending six percent; Ford (F) and Chrysler dropped 22 percent each.

MediaPost has the full gory details.

[Image Credit: Hauke Sandhaus]