I would opt for the gas Signature. The diesel may be cheaper now but I’d be worried about the cost of potential repairs (as well as the extra cost of diesel). You’re going to put 100k miles on that car in five years. Your powertrain warranty will be gone at 3 years. This is a one year only model and parts are going to be a nightmare to source in the US. Service centers aren’t going to be familiar with how to work on the diesel.