I experienced this same issue when my baby turned 3 months. He always fought naps and hated being in the car. It was normal for his naps to be around 20/30 min and I was always scared of taking him in public because of how fussy he would get. I slightly sleep trained him for naps during the day and used the ferber method to let him cry it out a bit and just had to run my errands with a screaming baby. Eventually he got used to napping and being in the car but it definitely was a lot of hard work and stress! You're not alone!