Is an AWD Model S Necessary?

[NigelM]

Could be an interesting discussion why anyone would want/need an AWD Model S when they could buy a Model X on the same platform, anyone want to start a thread in the S or X section?

[richkae]

Could be an interesting discussion why anyone would want/need an AWD Model S when they could buy a Model X on the same platform, anyone want to start a thread in the S or X section?

Thread move bait:
A Model S will have more range than a Model X with the same battery. Some people don't need bigger.

[Trnsl8r]

Thread move bait:
A Model S will have more range than a Model X with the same battery. Some people don't need bigger.

And... an AWD Model S will have more range than a RWD Model S... due to more regen.

[MitchL]

And... an AWD Model S will have more range than a RWD Model S... due to more regen.

Sure about that?

The way I look at it is: the total amount of kinetic energy in the car to be converted back into electricity doesn't really change for AWD (assuming similar weight, speed), so I would not expect regen to be significantly different.

I suppose you could have much more aggressive regen with AWD, but at some point it's too much, right?

/Mitch.

[Trnsl8r]

Sure about that?

The way I look at it is: the total amount of kinetic energy in the car to be converted back into electricity doesn't really change for AWD (assuming similar weight, speed), so I would not expect regen to be significantly different.

I suppose you could have much more aggressive regen with AWD, but at some point it's too much, right?

/Mitch.

Pretty sure I read somewhere that the AWD version of Model X would have better range due to being able to regen-capture energy on both axels, but now I can't find the link...

[rolosrevenge]

I would buy an AWD Model S over a Model X. It adds additional performance and handling, especially in the snow, and the S will be cheaper than the X with the same sized pack. It's like my A6 Quattro, definitely not an off road vehicle, but I bought it for the AWD for snowy and slushy conditions.

[jerry33]

The way I look at it is: the total amount of kinetic energy in the car to be converted back into electricity doesn't really change for AWD (assuming similar weight, speed), so I would not expect regen to be significantly different.

This is my thought too.

Regeneration is better than throwing away the energy as heat the way that friction brakes do, but there are losses because the motor/generator and inverter heat up, so regeneration is not as good as using the kinetic energy to glide whenever possible. When gliding only the resistance of the bearings, tires, and wind steal the energy. I haven't seen numbers for the Tesla, but for the Prius only 33% to 50% is captured by regeneration (and things have to be perfect to approach 50%). I suspect the Tesla will capture more because the battery can take a higher level of charge, but every time you convert energy from one form to another there are losses. I'd love to see some actual measurements of this.

[Robert.Boston]

I haven't seen numbers for the Tesla, but for the Prius only 33% to 50% is captured by regeneration (and things have to be perfect to approach 50%). I suspect the Tesla will capture more because the battery can take a higher level of charge, but every time you convert energy from one form to another there are losses. I'd love to see some actual measurements of this.

Remember with the Prius, you can only access regeneration through the brake pedal. It would take a lot of skill to maximize regen without engaging the friction brake. This will not be an issue on the Model S. My recollection is that Roadster owners claim ~80% efficiency on regen.

[jerry33]

Remember with the Prius, you can only access regeneration through the brake pedal.

Regeneration also happens when you let your foot off the gas. It's not as strong of a regeneration as Tesla, but it's [expletive deleted] annoying because you have to educate your foot to press just the right amount so that you aren't regenerating--this takes a lot of practice to get right. I'd rather have the Prius' regeneration only on the brakes.

It would take a lot of skill to maximize regen without engaging the friction brake.

Disk brakes always touch the rotors so there is always a certain amount of friction braking. Not a lot of skill is required to get the most regeneration--just a bit of planning ahead so you don't roar up to the stop light and then stomp on the brakes like so many drivers do. However, it's better to avoid both the regeneration and the friction braking. In the Prius this is done by just holding the gas pedal at the point where there is neither power nor regeneration occurring. Additional instrumentation helps with this, as does a lot of practice.

My recollection is that Roadster owners claim ~80% efficiency on regen.

That is a number that I was looking for.

[bonnie1194]

So who wants to see if they can bring this new thread back on topic? Anyone?