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Frequently Asked Questions

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About cars21

  • Does cars21 cover all forms of electric vehicle types and hybrid technologies?
  • The focus of cars21 is on full electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) as truly next-generation vehicle technologies to be commercialised over the next few years. The hybrid electric vehicles (HEVs) already sold around the world are not the focus of cars21, although scientific papers and news may cover this area.

    As the name suggests, cars21 for now is mainly limited to light-duty (and heavy-duty) road vehicles, and neighborhood electric vehicles (NEVs). It does not cover e-bikes, scooters, boats, airplanes, military vehicles, submarines or trains.
  • What is the vision of cars21?
  • Our ultimate goal is to become THE business-to-business exchange and information hub for EVs/PHEVs. cars21 strives to be a global interactive platform for engineers, marketers, the supplying industry and OEMs, academia, decision makers and the public at large. Based on daily news and evolving products, services and knowledge sections, cars21 connects the community around the world and spurs an exchange of ideas to accelerate the market uptake of electric vehicles. All this makes "Cars for the 21st Century" a reality today.

Basic Facts

  • What is a full electric vehicle (EV)?
  • In very simple terms, pure electric vehicles (EVs) get all of the power they need to move from one or more electric motors. Unlike in internal combustion engine (ICE) vehicles operating with a particular fuel such as gasoline or diesel, an EV operates with energy stored in battery packs carried on board the vehicle. Hence, it does not have dual mechanical and electrical powertrains but rather 100% of its propulsion comes from electric motors. All-electric vehicles using only a battery pack and an electric motor to store energy and create power are called Battery Electric Vehicles (BEVs).
  • Where does the energy for an EV come from?
  • EVs use an on-board rechargeable electricity storage system (RESS). For now, most EVs operate on chemical energy stored in the vehicle's on-board battery packs battery electric vehicle (BEV). In the future, static energy stored in the vehicle in electric double-layer ultracapacitors or the storage of kinetic energy in a spinning flywheel, might come into use more often. Some EVs have also been combined with solar power roofs to provide additional energy.
  • What is a plug-in hybrid electric vehicle (PHEV)?
  • A plug-in hybrid electric vehicle usually makes use of both an on-board rechargeable electricity storage system (RESS) and a fuelled propulsion power source, an internal combustion engine (ICE) running on gasoline or diesel. The batteries of a PHEV can be charged externally - by connecting a plug to an electric power source - to displace some or all of their ICE power and gasoline fuel. PHEVs will allow for vehicles to store enough electricity (from an overnight charge) for the first tens of miles to be driven solely on electrical power. During the charge-depleting mode of the battery, PHEVs become all-electric vehicles, running solely on the power of the battery. PHEVs share the characteristics of both traditional hybrid electric models (HEVs), which use an internal combustion engine and an electric motor, and battery electric vehicles (BEVs), which also have a plug to connect to the electricity grid. Depending on the use of PHEVs, they are sometimes called grid-connected hybrids, gas-optional hybrids or GO-HEVs.
  • What is the difference between a plug-in hybrid and a "normal" hybrid car?
  • Electric hybrid vehicles - HEVs - usually combine a conventional internal combustion engine (ICE) with one or more electric motors. For modern HEVs, excess energy from the ICE will be transferred to a generator to either recharge the battery or directly feed power to the electric motor. When accelerating, both the ICE and the electric motor are working together, so that a smaller ICE is needed. When braking, part of the braking energy is transferred back to the battery to recharge it (regenerative braking). For many models, the ICE is shut down at idle and restarted when needed (start-stop system). There are full hybrid vehicles, mild hybrids and micro hybrids, depending on the grade of electrification and the construction of the powertrain, and consequently the emissions savings involved.

    Plug-in hybrid electric vehicles are different from "normal" hybrid vehicles in that they usually use a bigger battery that can be directly charged externally from the electricity grid. They are considered to be a hybrid between HEVs and EV, featuring characteristics from both technologies. The main difference between HEVs and PHEVs is that HEVs, already mass-marketed today, do not use any electricity from the grid. Versus non-hybrid vehicles, PHEVs can deliver a 40-65% improvement in fuel economy. This is significantly more than HEVs, which lead to 25-40% fuel savings on average.


  • What are the environmental benefits of EVs/PHEVs at a glance?
  • The use of EVs/PHEVs can bring about the following benefits:
    • Reduced air pollution
    • Reduced dependence on petroleum
    • Reduced use of fossil fuels, if electricity comes from renewable or nuclear sources
    • Reduced greenhouse gas emissions
    • Increased energy security
  • In detail, how can EVs/PHEVs help the environment?
  • Compared to conventional vehicles, PHEVs can reduce air pollution, dependence on petroleum and hence energy security, and greenhouse gas emissions contributing to global warming. Plug-in hybrids do not use fossil fuel during their all-electric range if their batteries are charged from nuclear or renewable energy sources.

    The "well-to-wheel" emissions of electric vehicles are lower than those from gasoline internal combustion vehicles. California Air Resources Board studies show that battery electric vehicles emit at least 67% lower greenhouse gases than gasoline cars - even more assuming renewables. A PHEV with only a 20-mile all-electric range is 62% lower.
  • Are EVs really zero-emission cars?
  • While electric cars are considered zero-emission-at-tailpipe-vehicles, their widespread uptake will eventually cause an increase in electrical generation needs. Depending on the source of energy used to generate this electricity, EVs might be significantly or only slightly less polluting than efficient gasoline, hybrid or diesel cars. In fact, if energy is taken from renewable sources, such as solar and wind energy, EVs can truly become zero-emission vehicles. EVs are therefore one of the most promising technologies to spur the use of renewable energies and stabilise fluctuating energy supply by storing this energy in the battery overnight.

    An example: Based on the assumption that most electricity in the US is from fossil sources, and half of that is from coal, a 70 to 80% energy efficiency of the EV becomes only 20% overall efficiency when recharged from fossil fuels.
  • Are plug-in hybrids cleaner (even on a coal grid)?
  • The 2007 EPRI-NRDC study for the US found that in under 9 scenarios for different rates of market penetration of PHEVs and the evolving power grid’s characteristics (capacity and carbon intensity), PHEVs will vastly reduce greenhouse gases for the next 40 years. A study from 2002 estimates that PHEVs using night-time power would reduce GHG by 46-61%.

    So even if, worst-case scenario, electricity were generated by coal, nationwide greenhouse gas emissions would go down and air quality for other emissions would improve.

Market & Costs

  • What are the benifits of EVs/PHEVs for the driver?
  • Lower fuel costs: The cost of electricity has been estimated at less than one quarter of the cost of gasoline. Using plug-in electric hybrid vehicles will therefore save costs on fuel, the use of full electric vehicles will avoid them altogether. Owning a PHEV is like having a second fuel tank that you always use first - only you fill up at home, from a regular outlet, at a cost equivalent to under $1/gallon.

    Lower lifetime costs: Lifetime service costs are lower for a vehicle that is mainly electric.

    Fewer fill-ups: Using only a small ICE or none at all requires less, if any, fuel fill-ups at the gas station.

    Home recharging: The convenience of home recharging or at the place of work increases comfort levels for the driver.

    Emergency backup power:
    Energy stored in the EV/PHEV battery can serve as a backup for emergency cases. A PHEV can provide power to an entire home in case of an outage; a fleet of PHEVs could power critical systems during emergencies.

    Vehicle to grid applications: As vehicles become increasingly electrified, there is an emerging opportunity for vehicle owners to sell electricity back to the grid to balance fluctuations in load and adapt to equipment failures. Typically, light vehicles are only used 4% of the time for transport. Assuming that future PHEVs and EVs will be similarly utilized, there is potential for them to be connected to the grid (in the garage or in an office parking lot) for some portion of the remaining 96% of the time.

    Cleaner & quieter: Compared to conventional non-hybrid cars, EVs and PHEVs are a lot quieter. Long driving distance: Batteries available today will provide about 100 miles of range. This is sufficient for most driving needs in the US, with motorists travelling on average 32.7 miles per day. In Europe, EVs are even more attractive as the average daily drive is around 17 miles (27 km). That means, EVs can cover 95% of typical daily driving needs. A PHEV, combining the ICE and the electric motor, can go even further. For local and regional travel, there is almost no need to gas-up.
  • How much more cost-efficient are EVs/PHEVs?
  • The cost of electricity to power PHEVs for all-electric operation has been estimated at less than one quarter of the cost of gasoline. At $3 a gallon of gas, driving a non-hybrid car costs 8-20 cents per mile. A PHEV only accounts for 2-4 cents/mile.

    In addition, PHEVs are meant to plug-in at night. In many countries, overnight power is available at a lower cost. Electricity providers may offer reduced night-time rates to incentivise off-peak charging, once PHEVs hit the road. In areas with wind and hydropower normally wasted at night, the rate can be as low as 2-3 cents per kWh. That would translate to 20-25 cents per gallon.