I hate to be a pedant (actually, that’s a lie; I love to be a pedant), but “inelastic,” as it was used to refer to car sales, does not mean sales aren’t seasonal. Rather, it would mean that sales don’t change much in response to price. I would say the elasticity of car prices is somewhere in the middle; cigarette prices are very inelastic (if the price goes up, it doesn’t affect demand much). At the other extreme, say, ice cream is very elastic: if its price went up considerably, many people would stop buying it. If car prices went up uniformly across the board, demand would definitely go down (people would keep their old cars instead of buying a new one), but not a lot (if your car is beat, you have little choice but to buy one, regardless of its price).
The column being referred to is: http://www.straightdope.com/mailbag/mcarbuy.html
Please, gang, if you’d post a link to the column, you would save everyone else lots of time – they’d be able to read the column before commenting on your post.