purr like a cat

purr like a cat

 and purr like a kitten 
1. Fig. [for an engine] to run well and smoothly. My car really purred after I got it tuned up. New sparkplugs and this old heap will really purr like a cat.
2. Fig. [for a person] to be very pleased, and perhaps moan or purr with pleasure. She was so pleased that she purred like a cat. Sarah really purrs like a kitten when she is happy.
See also: cat, like, purr

purr (like a cat)

in. [for an engine] to run well and smoothly. New spark plugs and this old heap will really purr like a cat.
See also: cat, like, purr