In January, conditions shouldn’t be that bad since it won’t be too rainy, but the road to Monteverde is pretty rough all year round. When we’ve visited, we’ve been very glad to have 4×4 with higher clearance for the steep hills, rough dirt, and potholes. That said, you could probably get away with a 4×2 SUV to save at least a little money. We have seen regular cars make it there too, but it’s not something we would recommend.
If you haven’t already, make sure to check out our rental car discount. We work with a company here and get our readers and clients a discount that usually works out to 10-25% off. Here’s a link to our site with more info: https://www.twoweeksincostarica.com/costa-rica-rental-car-discount/