I think the general consensus here is to avoid early ASR cars. While some have had moderate success with the system, other have found it to be a pure annoyance. I went through a Canadian winter in my non ASR equipped '89 300CE and had no problems (never got stuck). I was equipped with four snow tires and some weight in the trunk. I believe the button on the dash with the tire is when you have the car equipped with snow chains and you need to inhibit ASR. ASR should come up in the Russian VIN decoder as it was an optional feature. Though I have never driven an M104, I enjoy the M103. Plenty of power, smooth and fairly durable (head gasket issues aside). You also won't have to worry about engine wiring harness like on the M104. On the E420, ASR will be a benefit since you will loose traction fairly quickly in wet or slippery conditions, and I think the majority of the 400Es and E420s have it anyways.