2002 325XI Vs. 325I

I'm about to order a new 2002 325 wagon and am considering the all-wheel drive XI version. Even though I live in a Southern climate and very little ice or snow will cover my path I'm sure the extra footing will help in rain slick conditions. One concern, I been told by my local BMW dealer that the XI's all-wheel drive system will NOT rob any of the existing thrust from the engine as compared to the normal rear-wheel drive of the I version. Can anyone confirm or dispute this? Unfortunately there isn't a 325XI on hand to test drive. The power of the 2.5L in a rear-wheel drive config. is adequate but I wouldn't want to lose any. Can someone shed some light on this for me. Thx.

The 325i wagon does 0-60 in 7.4s manual, 8.5s automatic.
The 325xi wagon does 0-60 in 7.8s manual, 9.0s automatic.

The dealer is incorrect about the performance difference between the two. I think most of the performance difference stems from the weight difference between the 325i and the 325xi.

Thx for the info EdgarFan659. I thought it very likely that a minor power loss was required for the gain of 4 wheel traction.