So I've been researching a the 5.7 vs the Diesel. Warning, long read and math ahead. But when you're about to spend $65k+, why not read a little more?
According to user posts on these forms and YouTube video fuel efficiency tests, the 5.7l V8 Rebel gets anywhere from 15-18 combined average mpg, while the diesel gets anywhere from 22-26 combined.
The average person travels 12,000 miles average a year, so let's use that for our math:
The 5.7l would get you 12000 miles a year divided by 16mpg, equalling 750 gallons of gas a year. Let's say you only use 87 as a way to save money. The average for 87 here in Az is $4.29. Obviously gas will fluctuate, but for the sake of simplicity let's keep it average of $4.29. So, 750 gallons of 87 a year is $3217 a year in gas total.
The 3.0l diesel at 12000 miles a year/23 mpg = 521 gallons of gas a year. Average diesel here in Az is 4.83, so $4.83×521 gallons a year = $2520 spent on diesel a year. Also add in the extra costs of running a diesel: 12 bottles of DEF at $8 a bottle per 1k is +$96 a year. Also add an extra $100 for the oil change cost difference on diesels, and that's a total of $2716 a year.
$3217 to run a V8 - $2716 to run the diesel is the difference of $501 a year.
The diesel engine trim on th Ram website is $2700 more than the V8. That means $2700 cost difference divided by the $501 year difference between the engines would be 5.4 years to cover the cost difference. Meaning, after five and a half years of driving 12k and staying the average fuel efficiency, you'd finally have started to get the diesel to pay for itself.
Also note that there's a significant "fun factor" drop off between the diesel and the V8. And if you want a diesel but are looking at other brands, do note that from the videos I've watched, the Ram diesel is +2 seconds slower than the inline 6 GM diesel. So the Ram diesel is a slower engine overall. That said, it still performs well off road, and is a towing monster.
TLDR:
If you drive it longer than five years, and gas stays within about $.60 of eachother, and don't mind the complete drop in horsepower, then diesel doesn't seem to be a bad option on the Rebel, as long as you're fine with it losing a lot of fun factor.