Yes, on a new vehicle. Not common on a used vehicle. But the issue here is that the vehicle was reportedly sold "as is" which means that all faults are the responsiblity of the purchaser. No guarantee or warranties. It is a buyer-beware situation. That puts the onus squarely on the purchaser to validate the condition of the vehicle they are purchasing.

If it was misrepresented by the seller (and it appears it was) then that is the avenue that the purchaser has to resolve the situation. The sad part is that the OP reported that he has nothing in writing, it was all by telephone. That doesn't remove the obligation of the seller to be truthful, but it does make it very difficult to prove anything.

On the upside, and it is a small upside, there is one CPO 4.8is on the BMWNA web site that has similar miles. It is listed at $36,000. This one sold for $27,000. So, $10k in repairs puts the two vehicles in the same ballpark. The OP would have been better off to buy a CPO vehicle, and do his homework, prior to purchasing, but he appears to have bought it cheaply enough to fund some repairs.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue