| Answer | Crossword Clue |
|---|---|
| HUM | Run smoothly, as an engine |
| PURR | Run smoothly, as an engine |
| PURRS | Runs smoothly, as an engine |
| PURRED | Ran smoothly, as an engine |
| IDLE | Barely run, as an engine |
| SPUTTER | Run roughly, as an engine |
| PURR | Run well, as an engine |
| TUNEDUP | Made run better, as an engine |
| PURR | Run like a charm, as an engine |
