| Clue | Source | Date |
|---|---|---|
| Electric vehicles, e.g | Universal | 05 Feb 2023 |
| Electric vehicles, e.g | Universal | 09 Oct 2021 |
| Nissan Leaf and Toyota Prius | LA Times Daily | 17 Sep 2020 |
| Nissan Leaf and Toyota Prius | The Washington Post | 17 Sep 2020 |
| 'Green' vehicles | USA Today | 21 May 2019 |
| "Green" vehicles | ||
| Fuel-efficient vehicles | New York Times | 10 Jul 2017 |
| Fuel-efficient vehicles | ||
| Prius and Volt | ||
| High-m.p.g. vehicles |