A few CNG-powered trucks in my hometown

Compressed Natural Gas, or CNG, was initially deployed as an automotive fuel in Italy during the inter-wars period, and is currently pointed as one of the easiest-to-implement measures to reduce the dependence on Middle-East oil, alongside ethanol. It's usually extracted from fossil reserves, either in oil wells or isolated, but since its basic component is Methane gas it can also be sourced from any organic matter residue in landfills and wastewater treatment plants. It's often also pointed as more sustainable than ethanol and biodiesel, because its impact on food prices and availability is lower. The main markets for CNG-powered vehicles nowadays are India, Pakistan, Argentina and Brazil. Their presence in Europe and the USA is increasing in commercial vehicles, but is still not so popular among private car owners due to the lack of refuelling stations in spite of the availability of Natural Gas as for stationary applications such as power generation, home heating and cooking fuel. Anyway, the folks at Ecomodder and CNGChat might like these ones...

Brazilian versions of the Chevy S10 have an Opel-designed 4-cyl engine available, initially as gasoline-powered but gasoline/ethanol flexfuel since '05, instead of the Vortec 2200 from their American equivalent. This on was originally a flexfuel, so now with the CNG setup it became tri-fuel capable...

This other S10 has the 4.3L V6 engine, and the CNG tank is visible at the pick-up box. Couldn't see any underbody tank, but since the spare tyre had been relocated to the box it may have released some space to fit other tanks, which would be kinda useful considering the thirst of the V6...

Another V6, this time a single-cab. Also fitted with a single box-mounted tank, but since it didn't have clearance issues with the wheel wells a bigger tank could be fitted...

The Dodge Dakota is considered a lemon in Brazil, because its local production run had been too short ('99-'01) and, in spite of running on the American 4WD chassis and suspension setup due to the harsher pavement conditions, it was only available in 2WD. It was also kinda expensive when new, and all of its gasoline-powered engines were imported. The 4-cyl 2.5L and the 3.9L V6 were made in the USA while the 5.2L V8 came from Venezuela. The only Brazilian-made engine was the Diesel-powered one, a VM Motori R425 OHV license-made by Detoilet Detroit Diesel which had some overheating issues and was more expensive to overhaul than the Diesel engines used in its opponents, leading a handful of owners to repower them with engines from other similarly-sized trucks such as the MWM Sprint 4.07 TCA used in the S10 from '99 to '05 and the Toyota 3L and 5L-E from the Hilux. Many of the surviving gasoline-powered ones had been converted to CNG, such as this one with extended cab and the V6 engine.

This double-cab Ranger was available only in South American RHD markets (except French Guyana where a rebadged Euro-spec Mazda B-Series was sold as the Ranger) and Mexico, because the Ranger made in Argentina is available there since late '97. Ford even offered a CNG-prep package for the 2.3L 4-cyl engine in Brazil from '06 to '12, and a bi-fuel CNG installation was a factory option for the ones fitted with the 4.0L V6 engine in Venezuela from June '09 to early '12. There is a conversion shop certified by Ford to perform the service in Brazil, but the certified conversions had the CNG tank mounted in the pick-up box, while this one had a non-certified conversion with underbody tanks in the stock spare tyre location. At least the spare tyre takes less useful space in the box than a CNG tank would...

In spite of the side graphics suggesting that it could be an F-100, it's a Brazilian equivalent to the American F-250 and was known locally as F-1000. The last zero on the graphics would appear in the stock sheetmetal pick-up box if it wasn't converted to a wooden one. Engine is the gasoline-powered 300cu.in. inline-6, backed by a 5-speed manual transmission. This one was fitted with a single CNG tank mounted under the box, still visible from the sides or from the rear bumper gaps.