The fuel efficiency of International's Navistar truck line depends upon how you set the electronics and how the driver operates it. The most efficient ones are the Paystar line, which are also the smallest. International makes a full range of over the road trucks.
Www.utoGuide.com has a list of the top ten most fuel efficient pickup trucks for 2013. Www.shopautoweek.com also has a list of its top four most fuel efficient pickup trucks.
A very straightforward guide to the best fuel efficient trucks can be located at http://www.autoguide.com/auto-news/2012/02/top-10-most-fuel-efficient-pickup-trucks.html. It gives details on the best MPG trucks of 2013.
Hybrid trucks are definitely more fuel efficient than conventional gasoline powered trucks. Hybrid model trucks generally have up to 25% better fuel economy than their gasoline alternatives.
There hasn't really been a brand of semi trucks recognized as the most fuel efficient. Since they run on diesel a more efficient fuel, semi trucks already are more fuel efficient than cars in terms of size and power.
There are a number of different trucks that are safe as well as efficient. For a woman with children I would recommend a Ford or Toyota truck for her to purchase.
ford has sold most pickups
US News has the ranking for the best efficient cars. You can read them at http://usnews.rankingsandreviews.com/cars-trucks/rankings/Affordable-Small-Cars/
The superlative of efficient is "most efficient."
Aside from the Dodge Ram series and now discontinued Sterling Bullet, it's available in a wide range of medium and heavy duty trucks by most manufacturers - Freightliner, International, Ford, etc.
GMC trucks are the most popular,but Dodge and Ford also have brands of utility trucks,as do Chevrolet and freightliner,but GMC has the most extensive range.
The most popular Nissan Trucks to buy new include the Nissan Frontier, a compact pickup truck, and the Nissan Titan, a full sized pickup truck. Both range from 14-18 miles per gallon.
Most semi commercial trucks or delivery trucks can be 50 ft long.