There's a middle ground: Avoiding unnecessary acceleration & deceleration.

I don't hyper mile, but I do get far better gas consumption than rated. I let people merge, leave safe follow distances, and don't aggressively close traffic gaps which actually improves traffic flow by reducing waves of jams.

http://www.smartmotorist.com/traffic-and-safety-guideline/tr...

Mind you, I've been in cities where this type of behavior may get you murdered, but where I live this creates a more relaxing drive. If I feel like speeding I'll go to a race track :)

Wouldn't switching to neutral increase fuel usage?

When you're in gear, the engine is kept moving by the momentum of the car. When you switch into neutral and break the connection between the movement of the car and the engine, the vehicle has to use fuel to keep the engine moving and not stall. Yes, resistance will cause you to slow down quicker in gear than in neutral, but during that time you should be using basically no fuel compared to using the same amount of fuel that your vehicle would be using while idling if you're in neutral.

Basically, while you're coasting in gear, you're using the car's momentum to run the engine rather than fuel. When you switch to neutral, the car's momentum keeps the car moving forward, but the engine needs fuel to keep going.

EDIT: Popular Mechanics has an article on it http://www.popularmechanics.com/cars/hybrid-electric/a5977/c...

No. The Model S will break the car for regen purposes if you are in gear. So you will lose speed but get a tiny bit more energy added to the battery. It's better to just go into neutral because that whole process is inefficient.

I haven't had the privilege of driving a Tesla, but I have driven a Volvo prototype electric car[0] and it had two modes. One "emulate a petrol car" mode where letting off the accelerator would simulate engine braking (via regen). Then it had a "highway mode" where letting off the accelerator would just coast as if it was in neutral. The highway mode meant you could avoid wasting your momentum on a highway due to slight foot movements in speed regulation.

Do Tesla cars have something like this?

[0] http://www.plugincars.com/volvo-c30-electric

Depends how new it is and the car. Older cars still fueled the engine either way. Newer ones cut the fuel themselves, as you intimated.

I think the rule of thumb is that carburetor engines have simplified idle mechanism.

So realistically anything younger than 30 years is more fuel efficient. Also safer.