29" ebike. Giant or Merida, they are like Toyota, mostly reliable, well priced, most boring but normally well made. I have a Giant.. The more you pay normally the better you get with diminishing returns though. Maybe Trek as well ?
Depending on the front fork it will have a QR lever or a thru Axel, either way you'll be able to take the front off easily to load it into a car. Not so the back wheel albeit it can be done if you have to. Ebikes are heavy, onto the roof is probably out.
I remember reading once an interview with an Australian female MTB racer who used to race road and swapped to MTB, she said she tought it would be like riding a road bike on dirt trails and as she said, it's NOTHING like that.
If you take to it you'll be more in tune with a better bike to suit your needs in a couple more years. If you buy something too cheap you WILL be disappointed as it will let you down. Off road is much harder on the bike.