Below are some notable blended HFC mixtures. There exist many more (see list of refrigerants). All R-400 (R-4xx) and R-500 (R-5xx) hydroflurocarbons are blends, as noted above. 1  R-401A is a HCFC zeotropic blend of R-22, R-152a, and R-124. 2  It is designed as a replacement for R-12. R-401A is a HCFC zeotropic blend of R-22, R-152a, and R-124. 2  It is designed as a replacement for R-12. 3  R-404A is a HFC nearly azeotropic  blend of 52 wt.% R-143a, 44 wt.% R-125, and 4 wt.% R-134a. 4  It is designed as a replacement of R-22 and R-502 CFC.
Diesel vehicles may be making a comeback. Diesel engines are more fuel-efficient and have more low-end torque than similar-sized gasoline engines, and diesel fuel contains roughly 10% to 15% more energy than gasoline. So, diesel vehicles can often go about 20% to 35% farther on a gallon of fuel than their gasoline counterparts. Plus, today's diesel vehicles are much improved over diesels of the past.
In an effort to make the most fuel efficient vehicles, automakers are looking at smaller displacement engines, which have made it into plenty of compact and subcompact vehicles. The motors in these vehicles donât pack much power, or torque, and are all aimed to use the least amount of fuel. These cars are all ranked in order, right down to the cubic centimeter from most displacement, to least, so take a look below, to see the list of smallest engines available today. The subcompact Mazda2 is the first on our list, with the biggest engine here.