I’ve written before about “hidden price increases,” where the sticker price stays the same but the invoice price goes up. Though such increases, dealers’ margins on car have gotten smaller and smaller over the past 20 years. And when the dealer pays more, you tend to pay more, even if the sticker price remains the same.

The latest development: after cutting the margins on base prices to five percent or so a few years back, this year Volvo is cutting the margins on options from 14 percent to six percent.

For example, invoice on the V70’s $2,995 Premium Package was $2,575 last year. For the 2009 model year, it’s $2,815, essentially a hidden price increase of $240.

Now, the factory makes more money, sometimes far more money, on options than on the base car. But when these profits aren’t shared with the dealer, what incentive does the dealer have to sell you stuff you don’t want? So in a way, hidden price increases might actually be bad for the manufacturer and good for the consumer.