The Oil Drum

Further, warming your car up, for example to defog the windows in the morning, is essentially illegal (Ordnungswidrigkeit - a minor offense against the public order), and will definitely earn various reproaches from your neighbors.

While here, the cool people have remote control starters, so you can look out your home or office window and start your car without actually having to go outside. I know people who start up their cars remotely half an hour before they plan to use them. So they'll be nice and warm, and they won't have to scrape the windows.

I have lived in Japan for three years, and will be here for a few more years. Very few people turn their engine of at red lights, but public buses have been doing that in my city ever since oil becmae expensive (they didn't do this when I first arrived).
The main reason that Japan uses so little oil in comparison per capita with the U.S is because almost no houses have central heating here (or insulation strangely enough). Instead they use portable kerosene heaters for a few hours at a time (but not at night due to the high number of accidental carbon monoxide deaths, especially this winter). We also use a Kotatsu (heated table) and sit under that instead of heating the whole room. Most schools also don't have central heating but just use kerosene in periods.
Comuting distances are not as large either, and public transport is very efficiant and relatively cheap. Also in cities like Tokyo, cars are inconvenient for getting about on as opposed to subways. But because many families live communally (with grandparents, in laws, etc), many Japanese friends go to convenience stores and park outside them for several hours at a time as it is the only private alone time they get. And they idle the engine the whole time to keep the car warm or air conditioned depending on the season.

Natural gas is getting more expennsive here, and almost everyone I know has instant hot water heating devices using natural gas. My bill for hot water per month is about 4,000 yen ($33 U.S.D) and that is just for my showers (I live alone). And petrol is 168 yen per litre (Equates to $5.40 U.S.D per gallon). So at that price for natural gas and petroleum products no one is going to use it for something such as central heating.

I'll confirm it again. You don't see it as much on the city roads (in central Tokyo, for example) but it's routine out in the suburbs / countryside.

I'd caution against thinking you know anything about Japan from a 'Lost in Translation' business trip to Tokyo :)