Im not saying it’s anyone connected to Elizabeth who the vehicle was borrowed from. Let’s say Joe killed Elizabeth because Bob hired him to do it. Joe knows Pete is on vacation. Joe uses Pete’s truck during the commission of the crime. All of Pete’s friends know Pete was on vacation so there is no reason to think that it was his truck. Even if neighbors inform police about Pete’s truck, Pete has an alibi. I think there are endless scenarios for how the truck hasn’t been tied to the case even if the killer has a direct connection to Liz or Sergio.