Model S (Performance edition) 1/4 mile time

[Lloyd]

I am not an expert, but if I recall correctly skidpad G results are almost completely determined by the tires selected, as long as the chassis is at least reasonably well set up. So I am not expecting anything out of the ordinary for the Model S.

However, the low Cg will make actual driving extraordinary, with very little body lean in corners, also low squat and dive when accelerating and braking. The test results most affected should be slalom speeds and emergency lane change maneuvers. Actual everyday driving will be much more impressive than the numbers, making the "EV grin" even larger - as hard as that is to imagine!

GSP

I would think that with the low CG, and little body lean that all 4 wheels are going to be firmly in contact with the pavement during the skidpad test, resulting in higher numbers than we are used to seeing. I expect slalom speed to be impressive also. Can't wait for Roadster 3.0 !

 

[AnOutsider]

Can't wait for Roadster 3.0 !

You're not the only one... Hope it kicks a$$ in design, performance and tech

 

[Doug_G]

I would think that with the low CG, and little body lean that all 4 wheels are going to be firmly in contact with the pavement during the skidpad test, resulting in higher numbers than we are used to seeing. I expect slalom speed to be impressive also. Can't wait for Roadster 3.0 !

Yes if the car can keep more weight on the inside wheels you'll get a bit more grip.

 

[TEG]

The Wrightspeed X1, which you could almost call the original Tesla Roadster prototype has exceptional handling. It really is limited by the tires and road conditions. It can do 1.2g+ around corners...

 

[Zextraterrestrial]

you can get an old 914 to do 1.2g+ also w/ 245 on rears and 225 on the front. The weight distribution of the car makes a bit of a difference in handling too- 34/66 for the x1 vs 46/54 of the 914 (I'm not sure what the 'best' ratio is) The S should be awesome!

1/4 mile S time I am upping to better than 12s w/ the sport TC and a 'light' driver + maybe spare tire removed, Is there a spare?

 

[AnOutsider]

No spare as far as anyone can tell

 

[spatterso911]

Not sure I could see a sub 12s time in 1/4 mile. Most sedans in this class at 0-60 can hardly do better than 13 sec and I think that as you wring the electric motor out, HP and TQ drop off. I still cannot imagine this car doing much better than 12.6 sec. Sure wish I could see the power curves for this car. It would really be foretelling.

 

[Zextraterrestrial]

Ya, i think 12.6 is a pretty realistic #.

 

[rabar10]

Revised estimate. I actually put effort into this one...

• Took the earlier Model S max torque chart and entered it into Excel to get torque/HP at RPM.
• (EDIT gear ratio is posted as 9.73 on TM's site, adjusted below) Came up with a gear ratio guess of 10.3 based on outer tire diameter and max speed requirement to get torque/HP at speed.
• Grabbed the Roadster Efficiency and Range spreadsheet from JB's blog post, which has data in 2 MPH increments
• Made "Model S multiplier" coefficients for each of the losses there (ancillary, tires, aero, drivetrain). I based the tire loss multiplier off of the weight difference (assumed 4225 lbs for the Model S), and gave a best-guess shot at the others.
• Played with these numbers until I got the 65kWh range number around 230 miles at 55mph.
• Calculated kinetic-energy change required for each 2MPH increment based on vehicle weight (momentum, basically).
• Subtracted the steady-state losses at each speed from the max power available at that speed
• Averaged the power between each speed increment, and divided by the KE change to get a time estimate per 2MPH increment.
• Add the times up, double-check the ET at 60mph (I get 4.46 sec, sweet)
• Calculate distance per increment and sum that as well, and I get a quarter-mile time of...

12.78 sec @ 114.6 mph

EDIT: with proper 9.73 gear ratio, I get 12.95 sec @ 114.6 mph.
EDIT 2: adding 5% power-to-pavement losses at max power, I get 13.24 @ 112.6 mph. Revisionist predictions are fun!

I'm such a nerd.

 

[AnOutsider]

Good work man, way more than I could have done. Wish we could "pin" this post and reference it for later. Would be cool to see how close you came.

 

[spatterso911]

Impressive deductions. Will be curious once real world dyno and track data emerge to see if your numbers are in the ball park.

 

[ckessel]

[*]Came up with a gear ratio guess of 10.3 based on outer tire diameter and max speed requirement to get torque/HP at speed. (Initial guess was 10.6, but 10.3 results in 250 rpm ~= 2 MPH)

I haven't been following the thread much, but the Specs page says "Single speed fixed gear with 9.73:1 reduction ratio". Are we talking the same gear ratios or is your 10.3 some other type of gear ratio?

 

[rabar10]

Will be curious once real world dyno and track data emerge to see if your numbers are in the ball park.

As will I!

Just added a max-power loss coefficient to my spreadsheet since the torque/HP curve is at a motor dyno level.
If you assume 5% losses in getting max power to the asphalt (on top of the steady-state losses to maintain a given speed, which is already estimated), you get 13.06 @ 112.6mph.

 

[spatterso911]

I'm thinking that that is a lot closer to my "homeboy" estimate of low thirteens and around 105-110 mph.

 

[rabar10]

I haven't been following the thread much, but the Specs page says "Single speed fixed gear with 9.73:1 reduction ratio". Are we talking the same gear ratios or is your 10.3 some other type of gear ratio?

Good catch. Will adjust for that. Top speed looks to get closer to 140 if it lets you get to 16k RPM and you're on the 245/35R21 tire that TEG got a picture of (27.75-in diameter)

 

[Lloyd]

12.78 sec @ 114.6 mph

I'm such a nerd.

What... Only two decimal places!! Couldn't you be more accurate!! :tongue:

 

[rabar10]

Corrected above post with proper 9.73 gear ratio.

• Without modeling any max power losses, I get 12.95 sec @ 114.6 mph. But my modeled 0-60 drops to 4.7 sec.
• With a 5% power-to-pavement loss at max power, I get 13.24 @ 112.6 mph. Modeled 0-60 drops further to 4.9 sec.

Based on the 0-60 times being off now, I'm willing to bet that the torque number for performance S has gone up from the quoted 415N-m number to around 455N-m, with the knee at 6300RPM or 52mph. I think "just under 13" is still the best guess for now.

 

[ferrarimanf355]

I'd be happy if it's on par with the 2012 BMW M5. Any quarter mile times on that one?

 

[stopcrazypp]

I'd be happy if it's on par with the 2012 BMW M5. Any quarter mile times on that one?

The official BMW sourced specs, put it at 0-60 in 4.4 secs and 124 mph in 13.0 secs (which I assume corresponds to the 1/4 mile). So it seems it will be almost exactly the same as the Model S Performance in terms of "official" specs.
http://www.topspeed.com/cars/bmw/2012-bmw-m5-ar100010.html

Car and Driver did clock it at 0-60 in 3.7 secs and 1/4 mile in 12.0 secs@122mph. But they did need a couple of tries plus launch control (which the tester noted was really hard to engage) to accomplish that type of acceleration. In the Model S, you just floor it, no fiddling with the launch control required (this is off topic, but I wonder if a "launch control" mode is possible for the Model S and if it would help squeeze some more time out of the launch).
http://www.caranddriver.com/reviews/2013-bmw-m5-road-test-review

So I suspect unless the driver knows how to use the launch control well in the M5, a race between the two will be pretty close.

Although the new M5 does have higher peak torque (680 N·m@1,500 rpm) and peak power (418kW@6,000 – 7,000 rpm) . Curb weight is 1,945 kg (4,288 lb) so it might have a weight advantage too.

 

[Lloyd]

I'd be happy if it's on par with the 2012 BMW M5. Any quarter mile times on that one?

Found on the BMW blog HERE 3.7 seconds