Range is a function of the tank. Tanks can be measured in gge (gallon of gas equivilent) and multiple tanks can be added to improve range ... the trade off is space. Larger vehicles such as trucks can make this trade of a lot easier than a mini-cooper.
I should disclose that I plan to convert my truck to NG as prices here in Colorado run between $0.85 to $1.35 / gge. On a 15 mpg truck, that can add up to a huge difference. ON a 40 mpg hybrid, not so much.
How much does it cost to convert a vehicle to natural gas? Also how many fueling stations are there around Colorado? (I’m in Arvada, and have a fairly thirsty Caddy).