On Sunday January 12, I was driving the vehicle on the highway with my cruise control on. The engine started missing the speed dropped a bit as the cruise control would not hold the speed. A mile or so later the vehicle engine started knocking with a metallic sound. I pulled over at the next exit and stopped at a store to look at the engine. There was nothing loose and a deep metallic knocking coming from the engine block, so I shut off the vehicle and called OnStar. At no time did any warning lights or other indicators come on. The gauges were normal. They/OnStar indicated I should not drive the vehicle, and they will tow to nearest Chevy Dealer for service and give me a $50 credit to take a Lyft to local airport to get a rental car. I was almost 4 hours away from home as I was travelling. After a week of turmoil with the local dealership I was told the vehicle needs a new engine. There is no ETA on the new engine as GM has to build it and has parts shortages. This was 5 weeks ago. I have been driving a rental since and there is still no indicate from the dealership about what happened or why. The vehicle is a 2023 and still under warranty but I am having to pay for the rental and request reimbursement which hasn’t happened to date. There is very little information available, and I am in no man’s land without a vehicle, so I have an open ended rental situation.