diesel fuel heaters BS ?

[wildplumdx]

just been looking on the net at diesel fuel heaters as in it passes through a heater before getting to your engine ? giving you better fuel mileage etc ? BS ? seems like it to me..... what are your thoughts ?

http://www.aliexpress.com/item/Fuel-Hea ... 65674.html
http://www.aliexpress.com/item/Fuel-hea ... 53803.html

[crazyclark31]

they are mostly desgined for cold climates. ie canada etc. Otherwise it is b/s. Driving style and vehcile set up/condition play the biggest part in economy.

[tweake]

as above.
don't forget some vehicles come with them fitted from factory. so you might get some 2nd hand. eg toyotas winter pack.