Highway Range Ignorance

[dsm363]

I think the 60 kWh pack is the sweet spot as well and is the way Tesla is positioning it. I agree with Alan.

[WhiteKnight]

My thinking exactly WhiteKnight. This is the second biggest obstacle keeping me from putting a deposit right now. The first being it's about $20-30k more than I realistically should be paying for a car. The bells and whistles and the EV coolness just can't get this car over the line in my mind. I live out in the middle of the desert. The 160mile version would be perfect for my daily commute (maybe 15-20 miles round trip) but I'd be trapped in town if something were to happen to my other ICE car. Yes this scenario is very improbable, but it happened to me last Christmas when my primary car was in an accident and I had to rely on the second daily commuter for the road trip to the in-laws.

Set aside a little money for a car rental fund and then you don't have to worry. Like Alan said, you'll be loving the Model S 99% of the time!!

[Robert.Boston]

You will notice a difference between 0 to 60 in 6.5 vs 5.9 and that difference is something you will enjoy every time you use the car. I dont know if anyone has figures for say 50 to 80mph but that makes a lot of difference when it comes to overtaking so is something I would want to know about when choosing between the different models.

Alan, you raise a great point. 0-60 mph isn't particularly useful in every-day driving (although there're a few places at toll plazas where 10-70 mph is safe and fun). 0-40 mph is what I use most around the city; 50-80 mph is what I care about for highway.

If we assume that the powertrain is identical among the (non-sport) versions, the lower 0-60 performance is a result of limited current draw. Therefore, it's likely that 0-30 performance will be nearly identical across all three (or even slightly better with a smaller, lighter battery); the difference will lie entirely in the 30-60 half of the split. Which would further suggest a very stark difference in the 50-80 overtaking time among the three battery packs.

[daxz]

I've figured the CdA by taking the dimensions and images from web site and calculated how much area the silhouette took.
W x H x percent area of silhouette x Cd = CdA
77.3" x 56.5" x .81 x .225 = 5.53 Model S
72.9" x 44.35" x .8 x .35 = 6.29 Roadster

Then I calculated the formulas from the roadster efficiency and range spread sheet and used the CdA ratios above
Wh/mile =
(179.9*v^-1.002) Ancillary Wh/mi
+ (-0.0003* v^2+0.0936*v +51.871) Tires Wh/mi
+ (0.02899* v^2 ) Aero Wh/mi [roadster has .0309 *v^2]
+ (0.006 * v^2 + 0.1669*v+51.667) Drivetrain Wh/mi
+ (24 Wh/mi) RoadsterToSAdjustment Wh/mi (57Wh/mi for 85kWh pack = 300miles @ 55mph)

dividing by pack size yields a mileage graph like:


At 75 Mph range is
40kWh= 114 miles
60kWh= 171 miles
85kWh= 243 or 225 miles -- the 85kWh pack was calculated 2 ways.
Where the @55mph = 300 miles and where the Ancillary+Tires+Drive Train curves had the same adjustment factor as the 40 & 60 kWh packs.

[ChadS]

This is not going to be your road trip car.

I completely get that it will not be your road-trip car.

But if Tesla builds out the Superchargers or allows access to CHAdeMO stations, it absolutely will be my road trip car. This is not because I do not understand how the car will perform on the road. It's because my current road trip car is a Roadster, and the Model S has more room and a little more range, both of which are very small peeves with the Roadster. The Roadster's charging speed is my only big peeve, and with Superchargers or at least CHAdeMO, it will be far better.

If you'd rather rent a gas car for long trips, I'm totally OK with that. But I'd rather spend some time along the way doing something outside of the car (which my wife would insist on even if we were in a gas car; and even by myself I often want to sleep, eat, visit friends, get exercise, etc). If I was in enough of a hurry so that didn't work, I'd fly.

[ljbad4life]

I completely get that it will not be your road-trip car.

But if Tesla builds out the Superchargers or allows access to CHAdeMO stations, it absolutely will be my road trip car. This is not because I do not understand how the car will perform on the road. It's because my current road trip car is a Roadster, and the Model S has more room and a little more range, both of which are very small peeves with the Roadster. The Roadster's charging speed is my only big peeve, and with Superchargers or at least CHAdeMO, it will be far better.

If you'd rather rent a gas car for long trips, I'm totally OK with that. But I'd rather spend some time along the way doing something outside of the car (which my wife would insist on even if we were in a gas car; and even by myself I often want to sleep, eat, visit friends, get exercise, etc). If I was in enough of a hurry so that didn't work, I'd fly.

Totally Agree. 250 mile range is perfect for my situation and many others. If it doesn't work for you move on.

[dpeilow]

I've figured the CdA by taking the dimensions and images from web site and calculated how much area the silhouette took.
W x H x percent area of silhouette x Cd = CdA
77.3" x 56.5" x .81 x .225 = 5.53 Model S
72.9" x 44.35" x .8 x .35 = 6.29 Roadster

Then I calculated the formulas from the roadster efficiency and range spread sheet and used the CdA ratios above
Wh/mile =
(179.9*v^-1.002) Ancillary Wh/mi
+ (-0.0003* v^2+0.0936*v +51.871) Tires Wh/mi
+ (0.02899* v^2 ) Aero Wh/mi [roadster has .0309 *v^2]
+ (0.006 * v^2 + 0.1669*v+51.667) Drivetrain Wh/mi
+ (24 Wh/mi) RoadsterToSAdjustment Wh/mi (57Wh/mi for 85kWh pack = 300miles @ 55mph)

This diving by pack size yields a mileage graph like:
Attachment 3739

At 75 Mph range is
40kWh= 114 miles
60kWh= 171 miles
85kWh= 243 or 225 miles -- the 85kWh pack was calculated 2 ways.
Where the 55 miles = 300 miles and where the Ancillary+Tires+Drive Train curves had the same adjustment factor (+24w above Roadster) as the 40 & 60 kWh packs.

For hypothetical trip of 340 miles 60kWh pack would need only 1 stop traveling at 70mph wasting .7 hours charging including 15 minutes to get get hooked up. You would need a charger at 190-210 mile mark though. The time you wait for long trips makes up for all the short 5+ minute detours to gas station currently.

Just flagging this post as it was caught in the trap.

[neroden]

Having just discovered this thread through a pointer...

WhiteKnight, I see what you're saying...I usually drive about 70-75 mph on the highway, like most people.

You clearly all live somewhere where the speed limits are higher.

However I realise that I'm making a compromise in one area (refueling speed) in order to get many benefits in other areas. With the superchargers, I still see the 85kWh pack as a road trip car. Yes, I'll have to drive a little slower (might take rural roads which typically have a speed limit around 55mph).

...looking at this, I think the model S is *exactly the right* road trip car for me.

First of all, New York State has a top speed limit of 65 on expressways. Forget 75.

Second, I already take rural roads -- speed limit 55 -- *by preference* over expressways. A drive down the uncrowded 5-and-20 to Cooperstown is a relaxing event, where one can comfortably pull off at any number of interesting tourist spots/shop/restaurants/etc. as one notices them, bringing back thoughts of classic road trips from the 20s to the 50s. A drive down the NYS Thruway (the parallel expressway) is a miserable slog interrupted only by taking an exit to an asphalt wasteland to get chain fast food....

Those of you who take fast expressways -- or even more extreme, autobahns -- for point-to-point trips will have to contend with the reduced range. For me, I think I'm going to get that full 320 mile range (with aero wheels).

[stopcrazypp]

Having just discovered this thread through a pointer...


You clearly all live somewhere where the speed limits are higher.



...looking at this, I think the model S is *exactly the right* road trip car for me.

First of all, New York State has a top speed limit of 65 on expressways. Forget 75.

Virginia (where Todd lives) raised their max speed limit to 70 (it was previously 65).
http://www.virginiadot.org/info/faq-speedlimits.asp

I live in California, where most roads have an absolute top speed limit of 65 (with 70mph only where posted, which is rare), yet most people drive 70-75mph anyways (especially in the far left fast lane; don't even try driving at 65mph in that lane, you will definitely get honked at). And CA isn't even one of those states that have explicit tolerance to adjust for speedometer error (a cop can pull you over for doing 66mph in a 65mph zone, although in real practice cops don't bother unless you are noticeably faster than the flow of traffic or at least 10mph over the posted limit). I guess in NY, people actually obey the speed limit (maybe the police actually enforce it strictly).

Second, I already take rural roads -- speed limit 55 -- *by preference* over expressways.

I know people who also take rural roads by preference. Its usually to avoid possible traffic jams from commuters/accidents on major highways. The rural roads take longer vs an ideal situation on typical highways, but you are pretty much 99% guaranteed to make the trip in the estimated time on a rural road, while on a highway the chance of a jam can be quite high (I've been caught in a few before).

[JohnQ]

This will be the hardest adjustment for me. I drive I-95 most often and I-81 through PA, usually between 75 and 80 mph depending on traffic conditions and speed limit. I've found that as long as I'm within 15 mph of the speed limit I'm not bothered.

Having grown up in SE Michigan, that speed is ingrained in me. Go to Detroit and drive to Ann Arbor or Jackson. If you're below 75 mph (the speed limit is 70 most of the way) you're getting your doors blown off.