I like the composite ones better, just get 4 and place in front of each wheel and drive on it. Now you have room on the sides to get under the car as well. I feel they are safer than wood. Harbor Freight sells them for under $30 for 2, use 20% off coupon on 2 purchases and it may not cost you that much. Now this will work on the x5 only because of the height, for lower cars yours will work better.

Looks like its doing the job though!

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2011 35d