I'm coming to the conclusion that the Tesla Model S windshields have a design flaw, in that they were not designed with electronic toll collection devices in mind, such EZ-PASS and the equivalent for other states. I know that the windshield has an infrared reflecting coating that blocks heat and that it also blocks the radio waves emitted by electronic toll collection devices. Other cars, such as Mercedes, have similar coatings, but their windshields have several square spots without such coatings specifically designed for toll collection devices. As one would expect, the service staff of other car companies know about these magic spots, and they are documented in manuals and even on video -see following link:
I've just inspected an S-Class Mercedes windshield at a local dealership and was able to see the square spots when I looked at it from a 30 degree angle in regular indoor light that was not too reflective. The windshield is a slightly different color (darker) within these squares and it is obvious that something is different there.I have spent a long time, under a variety of lighting conditions, looking for something similar on my Model S Tesla and have not seen been able to locate anything resembling the spots on the Mercedes. I can't help but conclude that there are no such spots on the Tesla S.
There are several Tesla threads and Tesla Club blogs that contain a variety of inconclusive personal opinions on where to place EZ-Pass-like transponders on the Model S windshield. The two spots that seem to be most popular are: right below the rear view mirror and on top of the dotted area to the right of the rear view mirror. I've tried both spots in my travels on the New Jersey and Pennsylvania turnpikes and have gotten inconsistent results; sometimes my transmitter registers at the toll booths and sometimes it doesn't. Whenever it doesn't register, I get charged a flat $5 fee instead of the $1-2 fee I should have gotten charged. So far, my EZ-PASS account has overcharged me somewhere close to $40. Talking to the EZ-PASS people about my problem has been a lot of fun. :(
I expect to get misinformation on blogs, but I expect more reliable information from the people who work at Tesla. Most of them have no clue about this issue. The people who work at the Owner Experience 800-line have their own varying opinions on where my EZ-PASS should be placed. One adviser (I'll protect his identity) wrote me the following in his email:
"I spoke with you yesterday regarding the placement of a transponder in the Model S. I talked with several different people before coming to the conclusion, directly under the rear view mirror is the ideal location for a transponder, or toll reader device. The area directly under the rear view mirror is lacking a coating which is applied to the rest of the windshield, thus allowing the signal to transmit more efficient."
Another adviser (I'll protect his identity as well), wrote me the following:
"Here’s the IR transponder install photo. It should help you install" This email included a photo showing that the transponder should go in the dotted area immediately to the right of the rear-view mirror. (I've checked with a local auto glass installer, who told me that the dotted area has a purpose - to block the sun when it is at an angle that would create a blind spot for the rear-view mirror. He could not find any spots on the windshield that looked like they were missing an infrared coating and shrugged his shoulders.)
So, the people on the front line of Tesla don't know any better than the individual owners who blogged about it.
MY SUSPICION IS THAT THERE IS NO SPOT ON THE MODEL S WINDSHIELD THAT WAS SPECIFICALLY DESIGNED FOR THE EZ-PASS-LIKE ELECTRONIC TOLL COLLECTION DEVICES. THE ENGINEERS FORGOT AND NO ONE WANTS TO ADMIT IT. OTHERWISE, WOULDN'T IT BE DOCUMENTED IN A SERVICE MEMO OR BETTER YET, AN OWNER'S MANUAL.
I love driving my Model S and think that for the most part, the car is extremely well engineered. However. I would appreciate it if Tesla would not allow the first few thousand owners to have to spend needlessly wasted time looking for a magic spot on the windshield that doesn't exist and paying many toll violations before discovering that there's something wrong. We're your best sales people- your ambassadors - your partners - be honest with us and get your act together on this.
My next step is to investigate the possibility of installing an outdoor EZ-PASS transponder. It is usually installed on the front license plate, but we don't have front license plates in Pennsylvania. So, I'm going to try to install it underneath the black plastic piece on the front of the car. I'm hoping that my local service manager will help me with that.