20100707-an-209It was Andy Warhol who suggested, back in 1968, that everyone would be famous for 15 minutes.

Today I was famous for 15 seconds. That's the effect of recession, I guess.

My moment of national celebrity came on Simon Mayo's Radio 2 drivetime show, which includes a feature called Homework Sucks. Listeners send in questions – often related to their kids' school work – and answers are invited. And they like to get a definitive answer from 'an expert'.

Today's question was right up my street: is it more fuel-efficient to drive a car with the air conditioning on or the windows open?

So I was on the phone to the studio (above) with an answer.

"There are really two answers," I said.

"If you go slowly you're better off opening the windows, and if you want to go quickly like down a motorway, then you're better off using aircon."

"It's all about air resistance and if you open the windows it disturbs the airflow around the car, and uses up more fuel."

What's remarkable is not so much my quarter-minute of waffle but the reaction to it from friends and colleagues.

I could get used to fame, if it only happens in 15-second bursts.