What’s the best way to increase a car’s horsepower?
Asahi, your grandpa is such an energetic person, isn't he?
I tinkered with my lawnmower for about four years and now it has 450 horsepower.
This word was probably made pretty recently. A horse's power? That is horsepower.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Take note that the reading for 力 is the りき version of the reading. You can remember this by thinking about how it's Ricky who drives the high horsepower cars. Vroom vroom Ricky!