A lot of legroom refers to ample space between the seats in an aircraft, vehicle or venue that allows passengers to stretch out their legs comfortably. Full definition
Plenty of cargo space and also a spacious backseat with lots of legroom. (autolist.com)
Lots of legroom in the front and back seats. (cars.com)
It looks great for providing lots of legroom for bigger babies, but it means that the seat isn't practical for parents with small vehicles and / or tall drivers. (albeebaby.com)