Answer
Deisel is 100% worth it even in cold climates. deisels are the most fuel efficient mass produced engines on the market. they far exceed even the efficiency of hybrids. hp/tq to fuel ratio is incredible. deisel engines are also known for long term durability. 300k miles is nothing for a well maintained deisel. it could well be the last car you ever need to buy.as far as not being nice for cold climates;deisel engines also have "glow plugs" which heat up the engine block when turning the key to the "on" position. only in (alaska winter) cold climates do you need a tank, or block heater.