Neither of our MB's have a remote start. The C230 can't be equipped with one anyway, and the 190E doesn't have one either. See a couple posts above for why (not the best solution).
That said, our ol' Mazda 626 has one. Pure convience, but only used occasionaly. One nice benefit is it's a multi channel unit with remote locking/unlocking and trunk release.
Also, the Mazda sits outside, even in -40, and if we're using the car, I start it a couple minutes before leaving to make sure of good drivability.
Both MB's sit garaged, and have access to a plug in for block heater use. MB's have super block heaters, and generally I have heat before the end of the street.
As to a late BMW 5-series, I can't remember the specific key encoding for that car. (I SHOULD, since we owned a 1997 528i!!). I think the system requires an additional key to be "cut" and the encoding is difficult to get around.
Also with the BMW, all the notes about using the right equipment should be followed. A BMW is as complex as a Mercedes, and it's electrical components are just as expensive. BMW's also use sophisticated ignition systems, and baring/poking wires to get a tach point is also a no-no. One thing that makes installation more difficult is the need to accurately measure RPM, which is quite a task on MB and BMW cars. SRS systems are also complex, using multiple sensors. This means a greater likelihood of stabbing an SRS wire.
Some BMW cars have key-specific memory systems that allow different drivers to program their cars and have the car save the settings using the key as the trigger. These systems can get screwed up during the process of bypassing the factory anti-theft, and it takes some care to make it work properly.
BMW cars also have expensive interior panels and materials. A goof is an expensive goof.
BMW cars also have traction control systems, which, for some reason, seem easily damaged by adding electronics to the car. Dodge Intrepid systems are really delicate, and we refused to work on such cars.
And don't forget about safety systems. Don't install a unit that won't deactivate when the hood is opened, the brake stepped on, the shift lever moved, or an RPM threshold exceeded.
Also, a good install means a good "start." This means that the unit disengages the moment the engine is catching, to keep from grinding the starter. This is the programming of the unit, and the quality of the tach measuring pick ups. A good installer will have the starter disengage immediately based on trial and error for EVERY car, not just model by model. We used all kinds of tricks to get good starts, including altering number of cylinder reads. This takes experience that most part time kids just don't have. Again, if it's a Neon, who cares?
One thing I don't like is that we put lots of time and energy into defeating the factory anti-theft. This is import to think about. You have less theft protection when a remote-start is installed, no matter what the shop tells you about on-board anti-theft witht he remote start. The MB and BMW factory systems are good, really good. Later ones are better than ANY aftermarket system, especially when GPS tracking is involved.
One other thing to note: Despite the availability of gear and people that will install it, don't put one in a manual transmission car. No! Never!
1998 C230 "Black Betty"