DD3 hated the car with a passion. She screamed herself blue in the face on the trip home from the hospital at the age of two days. We were crawling along in rush hour traffic and the other DCs fell silent and started sucking their thumbs. The second the car stopped she stopped crying and gave a little sigh. It didn't get better until she was about 2, sorry to say.
I used to have to travel to a supermarket twenty minutes away for groceries, and by the time we got there she would be literally in a lather from screeching and sobbing. I would spend twenty minutes breastfeeding her and calming her down in the van, and we would then proceed to try to shop. She hated going in the trolley in her carseat too.
I didn't know if it was the sensation of moving while on her back or the view of the lights and girders in the ceiling, or the muzak -- she reduced entire sections of the supermarket to silence just as she had done to her siblings, and people used to look at me as if I was a cruel, horrible mother, when I was just trying to get the damn shopping done in one trip to save everyone a repeat of the horror of it all until the next week. Even so, I often ended up forgetting things despite having a list, as the distraction of it all was too much.
It was really difficult for me to have her in a front sling and shop, as leaning down to get items from the lower shelves was hard with a sling and a baby in it who didn't brace herself for changes in position like that, and some things required two hands to pick up. The older DCs were my little shopping helpers.
When she started sitting up I got a back carrier that she could sit in, and this was a little better even though it didn't fit me very well (it was stupidly designed, I think with the proportions of someone taller than 5'6" in mind perhaps a dad and not a mum?). Sitting up in her back carrier, she would play with a chunky bead necklace that I used to wear around my neck just to give her something to manipulate and chew, and pull my hair. I also attached other little toys securely to the carrier. I didn't care how I looked. It was difficult to get her into it when we shopped I had a van and had to set it down in the boot, put her in and fasten the straps, then sit down and hoist it onto my back, and off we would go. She also used to shift her weight from side to side and could sort of stand up or bounce by wedging her feet against the waist strap -- my back hurt a lot but it was worth it. I had to use the back carrier for her while I did housework and cooking too. It was very handy for the park and lifting the older ones onto swings or rescuing them from places they had climbed to. Weirdly enough, she liked the baby swings. (Many good memories of her happy little face).
She improved in the supermarket when she got big enough to sit in the trolley seat, though she protested very loudly about going in, stiffened herself and resisted stoutly when she got to the terrible two stage. I often enlisted the help of supermarket staff/security staff to cajole her into co-operation or to hold the trolley while I jammed her in, and I had to use a harness to make sure she didn't climb out. By that time she was sitting front facing in the car too, and not lying back.
I put her in the middle of the back seat so that the others could easily climb in on either side and so that I could see her in the mirror and she could see me. We used to sing a lot in the car together, and I had tapes (it was the late 90s and an old vehicle) that she liked. If we went on long car trips as a family I used to sit in the back with her and wear myself out entertaining her for the sake of everyone else's sanity (because obv mine was never in danger - hah!). We used to do a nine hour trip to see exFIL and MIL once a year and it was murder. They used to talk among themselves about why I was always so uptight when I visited, I later found out...
The screaming that accompanied car travel and shopping was just one aspect of a really intense, persistent, determined and nervous personality that mostly revealed itself in negative ways until she was about 4 (hence the carrier while cooking and housework, and she didn't sleep through the night until she was almost three), though there were a lot of good times too -- but it all seemed to turn positive after that as she became more amenable to reason (or maybe there were other factors and I am clueless). The positives as a baby and toddler were that she was really, really loving and liked to be close to me, loved to converse and sing and enjoyed rhymes. She has perfect pitch and now at 13 is a budding actress with a great sense of humour, a fantastic mimic who can nail tone and attitude. She still hates travelling fast, has a fear of trains, and sleepwalks occasionally.
Your friend may be in for a wild ride but that sort of personality has its rewards too.