Yosemite dirtbagging advice for not having bears break into cars?

I’m from the UK and coming to Yosemite for a month in a couple days and I’ll be staying in my hire car in El Portal. I’m planning to hire a couple bear boxes to keep my groceries in, but I’ve seen things about the bears sniffing out even food spilt like on children’s carseats?? Which makes me wonder how strict I need to be with like getting every scrap of food off my saucepans and stuff. 

Can anyone advise on how stringent it’s necessary to be/any necessary bear proofing habits for living out of a car and therefore having all food and cooking stuff in it? Surely people arent eating out all the time? 

Wasn’t sure how much I’d have to worry in el portal, until I saw this article mariposagazette.com/article… so now I’m wondering if there are any tips to be aware of, or if I need to seriously reconsider my eating plans. 

Keep nothing that is food, looks like food, or smells remotely like (or of) food in your vehicle.  That includes and food packaging or wrappers. Sunscreen sometimes can be mistaken by bears as food. Also, for both large furry mammals or human type -- don't keep things "in view" in your car.  

I put everything that looks or smells like food into a bear box or canister: food scraps, grocery bags, toothpaste, sunscreen, lotion, lip balm, soap; anything that smells sweet. I’ve seen cars destroyed by bears in California. All of those things can attract rodents to enter vehicles, too. 

Thanks, that’s so helpful! I will leave the window cracked and blow cigarette smoke into my car, screw it, whatever works haha! 

As for the bear canisters, I’ve read that when using them at campsites they should be left away from the tent. So can I keep a bear canister with food in it in the car? Or can the bears still smell the canisters and just not get into them?  

You don’t need to get any canisters yourself. Unless you’re backpacking. You can sleep with all your food and stuff with you in your car in el portal. When you go climbing for the day, leave food in a bear box that are located at many parking areas around the valley.

Personally, the only time I ever put stuff in a bear box in Yosemite is when I’m away from my car overnight. Overnight is by far the most common time to get “bear’d”. Even then, I usually leave my stove and cooking supplies in my car. Just be sure to cover it all so it’s out of sight. Yes, I’ve been lucky but have also spent hundreds of nights/days in the valley. Many others I know operate with a similar approach. 

"plain dumb luck"

If I remember correctly, in Yosemite 1/3 of the bear breakins of cars were cars that had no offending odors, food, sunscreen, etc. The implication is that even if you are doing everything right, if the last person driving a grey Honda Civic had a bag of tunafish sandwiches in the backseat, then your grey Honda Civic in the same parking lot gets a full bear search.

As an anecdotal data point, in Colorado I had a bear open a car door (unlocked) and drag my food bin 100 yards into the woods. It investigated but did not eat tea leaves or Mary's Gone Crackers. The bear came back the next night & I found it in the car looking for something more edible than that the Crackers that I had yet to discover in the underbrush. So maybe a diet of tea and crackers with no fat or salt will reduce bear attraction.

I just hide my food under my cocaine, bears love that sh1t.  

I take my food out at night and into a box. I also spray the car with ammonia. Hit bumpers, wheels and doors. 

Just buy the insurance on your rental car and don't worry about it.

More seriously, Brian is right.  Millions of people visit Yosemite every year and plenty of them are leaving food in their cars, and most of them are not getting raided by bears.  It's a risk, but not a huge one if you're reasonably careful.  Anything that looks like food (e.g. empty cup, plastic bag) should go in the trunk or buried under gear.  Avoid smelly foods. Use the bear boxes (aka bear proof food lockers) when you can (especially overnight).  If you're there in the car, you can scare the bear away.

Here's the park's page explaining the regulations:

https://www.nps.gov/yose/planyourvisit/bears.htm

https://www.nps.gov/yose/planyourvisit/lockers.htm