Earlier quoted context omitted.
You should never pay more than invoice for a new car. For that matter you should never buy a new car, it doesn't make economic sense.
> it doesn't make economic sense People repeat this a lot, but it isn't that cut and dry. People often ONLY include the direct cost of the two vehicles. They don't include the massively discounted loans on new vehicles (e.g. 0% APR), the warranties (e.g. 3-5 years bumper to bumper), sometimes better MPG (newer model, etc), cheaper insurance, skipping state inspection for the first three-five years, new tires & other…
Just to be clear, that's a GOOD thing. You want depreciation to happen NOT on your watch, BEFORE (or after) you own it.
Something that starts at $20,000 will lose a lot of value on your watch pretty quickly. Something that starts at $2,000 has already lost most of its value on someone else's watch and by the time you sell it you may only have lost say, $500 on depreciation. There's just not as much room to go down, and frankly if you keep replacing parts you can usually keep it going very economically for hundreds of thousands of miles, till the engine fails and needs rebuild/replace.
It takes a hell of a lot of savings on all those things you listed to make up the $18,000. It is especially common for people to way overpay for better MPG, when it would take decades to make it back (by which time they have another new car again)