|2006 Zafira CNG|
Opel (GM) is introducing the CNG version of the second-generation Zafira minivan line (introduced May 2005) at the upcoming Frankfurt auto show. The Zafira CNG is designed for optimal operation with natural gas, biogas or any mixture of the two.
Like its predecessor, the new Zafira CNG uses a 1.6-liter monovalent plus engine. This model, however, complies with Euro 4 emissions standards, as opposed to its predecessors Euro 3 conformance. That, coupled with a slightly larger vehicle design, and extra CNG tank capacity, results in slightly reduced performance and increased fuel consumption.
Natural gas vehicles tend to come in two versions: bivalent or monovalent. Bivalent vehicles are designed to drive both with natural gas and with gasoline. If the natural gas supply is exhausted, the engine switches automatically while driving to gasoline drive. (This is the approach BMW is using with its hydrogen 7-Series vehicle.)
Monovalent vehicles, on the other hand, operate only with natural gas, or with a small emergency tank for gasoline. The bivalent design produces longer driving ranges at the cost of a higher level of emissions and fuel consumption. The monovalent focus on natural gas allows for better fuel consumption and lower emissions, but a shorter driving range.
Opel’s CNG vehicles are monovalent; or monovalentplus to use Opel’s marketing term. These engines feature dual injection banks for gas and gasoline operation, with sequential injections. Special pistons support high compression, and special valve, valve guides and valve seats support natural gas combustion.
The new Zafira CNG (Zafira CNG–B), as it is called by Opel Special Vehicles, the offshoot of Opel that makes the CNG models) 1.6-liter engine produces 69 kW (93 hp) optimized for CNG. A 14-liter emergency gasoline tank provides the fuel for gasoline mode.
Switching between fuel operating modes is via a switch on the center console, or happens automatically when the primary fuel supply is too low.
|Zafira CNG Storage|
Opel increased the storage capacity of the tanks (stored under the floor of the van, as shown in the diagram at right) from 19 kg to 21 kg. This extra fuel capacity extends the driving range of the new Zafira to some 540 km (336 miles).
The new Zafira deliver 3% less power than the older model, and uses 6% more fuel: 5.3 kg of CNG per 100 kilometers, compared to 5.0 kg/100km. Correspondingly, CO2 emissions rise 7%, from 136 g/km to 145 g/km.
Even with the increase, the CO2 emissions from the CNG model are still 17% less than the 175 g/km from the 1.6-liter gasoline version, and 12% less than the 165 g/km emitted by the 1.9-liter CDTi diesel version.
The first Zafira, introduced in 1999, sold some 1.4 million units. Its CNG version was a leader in its sub-segment as well, selling 20,000 units. Every third natural gas car in Germany is a Zafira.
|First- and Second-Generation Zafira CNG|
|1st Gen CNG|
|2nd Gen CNG|
|2nd Gen Gasoline|
|Emissions||Euro 3||Euro 4||Euro 4|
|Power||71 kW (96 hp)||69 kW (92 hp)||77 kW (103 hp)|
|Fuel consumption||5.0 kg/100km||5.3 kg/100 km||7.2 l/100km|
|CO2||136 g/km||145 g/km||175 g/km|
|Top speed||170 km/h (106 mph)||163 km/h (101 mph)||197 km/h (122 mph)|
The marketing message for CNG vehicles in Europe has traditionally revolved around two points: the lower price of CNG, and the reductions in CO2 emissions. While the latter message point remains a strong one, the former is rapidly gaining in the context of market developments.
Opel estimates with the new Zafira CNG, given the relative costs of fuel in Europe, drivers can cut their fuel costs by approximately 50% percent compared to gasoline models, and even around 30% compared to diesel versions.