Here is what i see from carfax:
Owner 1: brand new, took a good care of the car, the car stayed clean, low miles.
Owner 2: dealer, auction, the car still stayed clean, low miles (2days of ownership)
Owner 3: travels a lot on highway, but the car still stayed clean because of the short time own.
You: the car looks clean but because of the owner 3 you got high mileage.
30K miles/a year sounds plausible. Thats about 82 miles/day. Not that much. I commute from NOVA to GreenBelt MD, thats about 40 miles oneway, 80miles/day. But i put them on 3 different cars.
Dont worry about it. If you ever find out your dealer cheated you (salvage, flood, junkyard titles) you could get about 10 brand new cars with a lawsuit, and their used car lot will be sold to open up a new McDonald.

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2002 X5 3.0 Siena Red
Premium, Cold Weather, Rear Climate Packages, 19" Wheels
Aluminum Running Boards, Clear Tail Lights, Clear Side Markers
Titanium Kidney Grills, Titanium Trunk Lid, Xenon Headlights
4.6is X5 exhausts, 35% Tint, Aluminum Pedals
2005 530I Mystic Blue
Premium Package, Sport Package, Xenon Headlights
18" Sport Wheels, 35% Tint all around
Mods to come: M-Tech Front Bumper, M5 Side Skirts, M5 Rear Bumper
Quad Exhausts, Style 172 19" Wheels