There's a tradition at the New York Auto Show held annually around Easter, which is the US' big showcase for performance and luxury cars.

The area is after all rich in well-paid professionals looking to turn their bonus checks into high performance playthings.

And big cars, particularly sports utility vehicles have enjoyed a fast rise in sales in the last 18 months.

Falling fuel prices have made consumers forget about the cost of running them.

But this year's New York show also betrays signs of a factor that's pushing auto-makers in another direction.

Government rules introduced in 2012 obliged US car makers nearly to double their vehicles average fuel efficiency by 2024.

Vehicles unveiled in the first day of this year's New York show were consequently a strange mix.

There were futuristic highly efficient vehicles like a new version of Toyota's Prius Hybrid.

There were also vehicles that would be just as at home on a race track as in an urban street, and road hogging-behemoths.

It's not clear how many people will buy the greener vehicles.

We have not seen people buy alternative fuel vehicles, um... hybrids as much EVs(electric vehicles).

But there may come a turning point in that, I don't know when that will be?

And there may have to be more government incentives.

To make that work, infrastructure changes have to be made especially for EVs.

I don't know when that turning point is, but we certainly are seeing more electrification of vehicles and the tide's got to shift at some point.

The clearest example of the resurgences of the big SUV was the unveiling of a new version of the Lincoln Navigator.

A SUV so vast and luxurious that when it first came out, rappers like to brag about owning one.

Yet the chief executive of Ford, Lincoln's parent, insist even this fast beast has been put on a diet.

What's under the hood of this concept is a 3.5 liter V6 engine. That puts out 400 horse power.

So traditionally in a vehicle this size, you'd have to put V8 engines or larger.

So clearly we wanna make sure in all of our vehicles and their respective segments,

they're either the best or among the best in terms of fuel economy in the segment.

Car makers in the US face a conflict between what they want to do and what they need to do.

What they want to do is meet resurgent consumer demand for expensive profitable sports utility vehicles.

Like this Lincoln Navigator.

What they need to do is to satisfy strict new US government fuel efficiency standards.

And to do that, they need to sell an awful lot more highly fuel efficient vehicles like the new Toyota Prius Prime behind me here.

The good news is that with US auto sales running at boom levels, car makers can afford to satisfy their desires and do what they have to.

The bad news is that with fuel prices at such low levels,

the exciting green cars on display here are going to be very rare sights on the roads indeed.

Robert Wright, Financial Times.

New York International Auto Show.