Hmm... preferred truck gets 8 mpg on a good day, down hill with a strong tail wind... daily driver truck gets 23 mpg...Savage with 15" apes still got right around 36 mpg the last time I rode it...
Insurance? Preferred truck no longer sees the pavement, so N/A... daily driver (plus her car with comprehensive) is $53/month... Bike is sub-$90 for a year.
Truck tires for the Ranger are $111/ea. Bike tire is $40. Dodge takes 9 qts of oil, bike takes 2. Dodge burns/loses about a quart between oil changes (really filter change and top off), bike a couple teaspoons. Ranger oil consumption is all over the place.
Does the bike save me any money? Not really, when I'm using it I tend to really pile on the miles, so annual operating costs are about the same for 98 Savage, 94 Ranger (4cyl 5 spd) and 69 D100 (318 w/auto 3 spd).
Real bonus to having the bike? I can mess with it to my heart's content and not have the wife fuss at me as much as when I mess with the trucks.