The new car issue. Imagine you run a car company. Your aim is to, well, make as much money as possible. To do that you have to
a) sell as many cars as possible
b) make as much profit on each car as possible.
To do a) you need to make sure your cars appeal to as many people as you can. So you make loads of options and variations within reason for your target markets. You also make your brand a desirable one.
To do b) you sell as many high end vehicles as you can.
Worked example - In the US BMW sell 325s as the base model, because it is a premium market and they make loads of money on every model sold. That is b) in action. In Europe the market is more about numbers, so they sell 316/318s not sold in the US. It costs BMW no more to make a 316 than it does to make a 325 but they sell it in large numbers - BMW sell more 3-series than Ford sell Mondeos. Thats a) in action.
An extreme example of b) in action is Porsche. Thats how they have the cash to think about buying VAG. Its also how Lotus never managed to be a 'British Porsche' although they think they are - they sell cars too cheaply - e.g. the Elise.
The problem with selling a car with mods aimed at eco-driving is that the idea is based on economy - and buyers in that market do not want to spend either on new cars or for cars with added features they don't think they need.
Take an average ecomodder for example - yourself even. You don't own a new car so Renault / BMW / SAAB have made little or no money from you. Secondly you will probably keep those cars for longer, so again apart from parts they make no money from you - you traitor
There are some real world examples. Take VW - they used to sell the Beetle in the US on the basis that it was reliable, long lasting but also economical. SAAB also sold solid, efficient and lightweight vehicles to discerning clients all over the world. In the Early 1970s when the oil price crunch hit, both of them should have been at an advantage yet at the same time both of them realised that to make a profit they needed to move upmarket. For SAAB it was the 99 and later the 900 models (away from the old 2-strokes), for VW it was the Golf/Rabbit and later the Passat and Audi models - away from the air-coolled flat-4. Part of this move was also labour costs - West Germany and Sweden are not cheap labour locations.
So as the head of a car company, can you really sell these things and expect to remain in position with shareholders baying for profits ?
There are examples of makers going for the low end though - my avatar's masterpiece - the original Mini - was aimed at sweeping the microcars caused by
Suez "back into the sea". The Citroen 2CV is a makers' response to their home market issues of low income and bad roads. The current Citroen C1 / 107 / Aygo is an example of selling a mainstream maker's car to a market normally dominated by the products of cheap makers like those from Indonesia, Taiwan etc.
As for pickups and trucks (F-150s) being sold in the US as the no.1 vehicle, wasn't this partly because the US offered a tax break to people owning one as a work vehicle ? My boss in the UK has just replaced his Range Rover supercharged with a "crew cab" Toyota for a similar tax break.
I love minimal motoring though. Original Mini, 2CV, Renault 4, Citroen C1, original Ford Ka - all superb in my book.