I drive separately.

I think in theory it's like, who cares?! But in reality, a MIL who insists she sit in the front and DH doesn't mind, it is weird. I've seen it twice, and in both cases the MIL believed she was more important than the wife. In those instances, I believe it's wrong.

If I drive, DH sits in front. If DH drives, his mom usually sits in front, unless the kids ask to have her in the back.

I think the bigger issue is that you care so much. Like you think it's a dig that she wants to sit up front.

I offer my MIL the front seat. She deserves quality time with my husband and it’s more comfortable for her to be in the front.

MiL in the back center between the kids by her choice. She always declines the front seat

I would typically offer MIL or FIL the front seat out of respect. Same with my parents. One of them may or may not accept. It is incredibly rude for your MIL to always insist.

I always let an older person sit in the front because it's generally more comfortable.

In our family, it depends. If it is just myself, my wife and my mother, usually my mother sits in the back and my wife sits in the front. If the kids are coming, then if Grandma or the kids want her to sit with the kids she does. If the kids want their mom to sit with them, Grandma sits in the front. We're pretty flexible and decide on a case-by-case basis who sits where. No one really has a preference either way.

It's weird for her to insist, but I offer my MIL whichever she prefers.

OMG. Who cares? You need to think about and appreciate how very very small your problems are.

Isn't it your car too? Owners get dibs on the front seat.

Omg that’s so weird! Unless she has some health issue where the front is more comfortable. Maybe she believes that elders should get the best seat?

I don’t think we have a rule. I think my MIL assumes she’s sitting in the back but sometimes I have her sit in the front, like if she hasn’t seen DH in a while and I want them to be able to catch up.

Normally DH and his dad sit in the front. They're 6'2 and it's just more comfortable. But yes, I'd probably give my MIL the front seat.

Curious how this is in your families. My MiL insists on sitting in the front next to her son (my husband). My husband sees nothing wrong with that.