You literally would have to be parking on a vertical slope for a full (proper) oil fill to register as low, even then, I don't think it would. For sure, the slope you're parking on is causing the level warning but it wouldn't if the proper amount of oil was in the sump to begin with.

My X5 came back over a quart low from an oil change. The level warning only came in when it was very cold before the engine warmed up.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim