On tv the other night, an auto-insurance company promised to lower my premiums by letting me “only pay for the features that I need.”

Another ad followed, where a health-insurance company promised the same thing. Together, the pitchwoman and I eliminated coverage for chiropractors, acupuncturists, alcoholism treatment (I don’t even drink), in-vitro fertilization, massage therapists and hairpieces. The she asked if I wanted to pay higher premiums to cut the premiums for people who wait until they are sick to buy coverage. (I passed.) All told, I saved $1,000 on a $7,000 policy.

Then she turned into my high-school calculus teacher and asked if I was ready to give my class presentation.

I awoke with a jolt — aware that I’d only dreamt the second ad. (And that it seems I’m still afraid of Mrs. DeConti.)

What I saw next was even scarier: The presidential debate, where Barack Obama told me how dangerous it would be to let me buy only the health-insurance features that I need.

Yet the fact that we can’t do that is a big reason why an estimated 46 million Americans lack health coverage.

For example, thanks to lobbying by chiropractors and the like, the average state requires you to buy 38 “mandated benefits,” like it or not.

A bigger problem are regulations that require you to pay higher premiums so that others can wait until they are sick to purchase insurance. Those “community rating” laws generally tax the young to subsidize the old — who have more money to begin with.

New York, New Jersey and other 19 states impose such laws. University of Pennsylvania economist Mark Pauly finds that they drive healthy people from the market, increase the number of uninsured — and do little to boost coverage for the sick.

Overall, the nonpartisan Congressional Budget Office says that state regulations boost premium costs an average of 15 percent.

Wouldn’t it be nice to be able to choose the features of your health policy, just like your auto insurance?

John McCain proposes to let you do just that, simply by letting you choose a plan available in another state. With the power to choose a policy regulated by a state with fewer mandated benefits and no community-rating laws, you could knock $1,000 off the price of a $7,000 plan.

This would boost coverage, too: A recent study by economists at the University of Minnesota suggests that McCain’s proposal could cover an added 12 million Americans.

But Obama sees choice as dangerous. He fears that “where there are no requirements for you to get cancer screenings,” no insurers would offer such coverage. The New Republic’s Jonathan Cohn echoes, “Less cancer screening under McCain’s plan? Actually, yes.”

Nonsense. California doesn’t mandate colon-cancer screening, yet Kaiser Permanente of Northern California is a leader in such research and boasts the most aggressive screening program in the country.

Michigan doesn’t mandate prostate or cervical cancer screening, yet six of the University of Michigan’s seven insurance offerings cover both. That’s where Cohn gets his insurance, so I’ll bet him a fancy dinner that he has coverage for both, even without a mandate.

Cohn fears California consumers couldn’t enforce protections crafted in, say, Delaware. Evidently, he’s never heard of contract law, which lets California courts do just that.

Cohn frets that scam artists would cheat unwitting consumers — yet McCain’s proposal would make fraud less likely. If insurance commissioners spent less time fixing prices and telling law-abiding people what kind of health insurance to buy, they’d have more resources to prosecute bad guys.

In the debate, Obama said, “We have a moral commitment as well as an economic imperative to do something about the health-care crisis.” Indeed we do. The first step is to treat consumers like adults, and stop letting special interests and the government choose our health insurance for us.