I recently purchased a 2003 S430, and am very happy with it overall.
I do have a few things to do...
One of the minor problems was that my cell phone had poorer performance inside the car. A little investigation revealed the special heat-control window glass that also hinders radio performance, including cell phone and GPS.
Since my home has marginal cell reception anyway, I wanted better cell performance. I decided to try a cell phone booster, in this case a Wilson Sleek 4G-V (for Verizon). I installed the system today, and did a minor amount of testing.
The booster claims to improve performance in three ways: An antenna outside the car (and those windows!); an amplifier for reception; and a booster for broadcasting. (I am not an expert in this field, and may well make a mess of this, but will be happy to hear any corrections.)
The benefits of an outside antenna are obvious, especially for those of us who have the special glass in our cars. I do not like the antenna provided with the booster! I like the performance improvement, but I do not like the cable running out the rear door and across the roof. I hope to do something about that soon, namely using the rear-bumper antenna built into the S430.
The reception amp increases the signal strength, then wirelessly links it to the phone. The phone must be resting in the booster, basically in contact with it. Reception is the only part of the system that I have actually tested so far.
First thing that I learned - bars mean virtually nothing. I found how to measure signal strength on my new phone (Razr Maxx HD), and used that to decide whether the booster actually did anything.
Sitting in my drive, phone in the car as usual (no booster used), I saw fluctuating readings for 4G (or LTE) reception, such as -112dBm, -106dBm, -103dBm, etc.
The dBm scale is logarithmic, which means that 3 dBm doubles or halves the field strength. Lower numbers are better.
I slipped the phone into the booster, and the numbers instantly changed. I still saw fluctuating readings for 4G/LTE reception, but now the numbers were -93dBm, -91dBm, -89dBm, -87dBm, etc. This gave an improvement of -10 to -15dBm. A -10 dBm improvement is roughly 10 times stronger, a -15dBm improvement is roughly 30 times stronger. The reception bars on the phone display sometimes showed one more bar, sometimes not. The Command phone display never changed, even with 30 times the field strength.
I repeated the brief tests on the 3G network. Reception is reportedly better on the slower network, and the numbers supported that. With no booster in use, I saw readings of -88dBm and -89dBm pretty consistently. When I slipped the phone into the booster, the readings immediately went to -66dBm, -68dBm, -65dBm, -64dBm, etc. This gave an improvement of about 21dBm, or a level 128 times stronger on the 3G network. Again, the improvement was not shown by changes in the reception bars in the phone or car displays - one bar most of the time, occasionally two bars on the phone, none on the Command display.
If I were depending upon the bar display, I would have immediately packed the Wilson up and sent it back! The phones testing display showed a very different picture, and I am confident that the booster does what it claims for reception.
I haven't tested broadcasting, and am not sure that I can. The claimed improvement will be easier for the booster to achieve, though. From what I could find, a hand-held usually puts out less than 100mW. The Wilson puts out 1.8 Watts...
I pulled everything out of the phone compartment in the center armrest except for the puck and its holder. The puck, booster and cell phone fit nicely, and I can pop the small lid open to operate the phone if necessary. (I use the Voice Command system for the phone.)
Next project is to get the booster hooked to the car's antenna, so I can get rid of the tacky cable on the roof.