The Oil Drum

It is routine in Germany to do this at a train crossing, even if only for a few seconds - along with the long rolling stop, motor idling. German cars are still mainly manual transmission equipped - Germans seem to hate automatics, and if you take a driving test using one, your license is restricted to automatics only.

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. However, such regulations are essentially local, and obviously not rigidly enforced - except for your neighbors' opinion, of course.

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 :)

Unless your engine speed really went up when the transmission went to neutral, it saved quite a bit.  (Coasting and idling in neutral is one of the ways I am able to beat the EPA numbers for my car by such a large margin.)

In Germany, it is a social difference - the main reason not to run the engine is based on environmental concerns, not fuel savings, though obviously the two are 'synergistic,' to use a favored expression of American business. As a side note - busses turn off their motors here at any bus stop if they will be waiting any appreciable amount of time, such as before the start of their route or at a rail crossing, but generally don't while in traffic. Sometimes, bus stops are changed as the people living near them complain so fiercely about the exhaust.