FASTSim: Future Automotive Systems Technology Simulator

FASTSim logo

The Future Automotive Systems Technology Simulator (FASTSimTM) provides a simple way to compare powertrains and estimate the impact of technology improvements on light-, medium-, and heavy-duty vehicle efficiency, performance, cost, and battery life.

This extremely fast simulation tool features a streamlined user interface and can rapidly perform a variety of tasks using basic computing resources:

  • <0.1 second to simulate second-by-second standard duty cycles
  • <10 seconds to estimate vehicle efficiency, fuel economy, acceleration, battery life, and cost
  • <5 minutes to perform powertrain comparisons of efficiency and cost.

FASTSim models a variety of vehicle powertrains and fuel converter types:

  • Conventional vehicles — spark ignition, Atkinson, diesel, and hybrid diesel
  • Electric-drive vehicles — hybrid, plug-in hybrid, and all-electric
  • Hydrogen fuel cell vehicles.

The default model includes a variety of vehicles and duty cycles and an option for adding additional vehicles and custom cycles:

  • Packaged with more than 20 vehicles
  • User interface enables addition of more vehicles
  • Includes standard U.S. drive cycles as well as European and Japanese cycles.

Download FASTSim

FASTSim is available for download in Microsoft Excel and Python formats.

Excel Version of FASTSim

Easy to Use, Enables Flexible Analysis

The Excel version of FASTSim features an easy-to-use, interactive interface that simplifies the process of importing new vehicle data and custom drive cycles. In addition to calculating energy consumption, the Excel version enables life-cycle cost comparisons, battery life comparisons, component sizing tradeoffs, design-of-experiment inquiries, and more.


Python Version of FASTSim

Compatible with Large Datasets

The Python version of FASTSim easily integrates with large duty-cycle databases. Pairing with the Transportation Secure Data Center, for example, facilitates multi-day simulations incorporating vehicle dwell times. When paired with geo-spatial cycles, FASTSim helps users draw conclusions at the regional level by incorporating such factors as temperature, roadway characteristics, or driving behavior.

Customizable for More Specific Analysis

The component models in the Python version are easily expandable and can be adjusted to incorporate additional energy consumption impacts. The model’s flexibility and speed simplify A/B comparisons for vehicle powertrains, control strategies, or technologies. Its large number of included vehicles and computational efficiency makes calculating impacts at the fleet-level easy.



While NREL does not provide technical support for FASTSim, we welcome your feedback on the tool. Please email your feedback or report any problems to


View publications that provide examples of how FASTSim can be used to evaluate real-world vehicle efficiency, compare powertrains, assess component improvements, or conduct other types of vehicle analyses.

How to Cite FASTSim

If you use FASTSim for work described in a publication, please notify us and include this citation in your publication:

Brooker, A., Gonder, J., Wang, L., Wood, E. et al., "FASTSim: A Model To Estimate Vehicle Efficiency, Cost, and Performance," SAE Technical Paper 2015-01-0973, 2015, doi:10.4271/2015-01-0973.

More Information

For more information about FASTSim, refer to these publications:

FASTSim: A Model to Estimate Vehicle Efficiency, Cost, and Performance

FASTSim Validation Report

FASTSim Overview Fact Sheet