I’d hardly call this a first world problem given the gravity of the situation but my shopping bag falls over when I corner as the fastening points in my estate are too low. This means I need to take as straight a route as possible home.
A short length of dyneema cord, colour coordinated to your upholstery, clipped to the handle of your shopping bag and the other end attached to your rear FM handle directly above.
I have a high-sided box kept in the boot and the larger loaded bags go in that, keeps them upright, otherwise if smallish they go behind the front seats in the footwells as others have said.
If you attach three sufficiently heavy orthogonally oriented flywheels to your car and spin them quickly enough during your shopping trips you should be able to prevent the kind of angular acceleration of the car which causes your shopping to fall over on your way home.
If you want to spend money on a product then there’s these ^^ Called Stayhold. Comes in various sizes. Velcro to the boot floor and even comes with a handy wine bottle holder if you’re feeling brave.
I thought I’d seen something like this before and a minute on amazon found them.
loads of space for my shopping to slide, get up momentum and then explode in a shower of tomatoes in the back of a transit.
i have a hooked ended camlock strap clipped to the headset of the passenger seat, and loop it around all the bag handles, and back to the headrest. Not hanging but certainly keeps them in place and supported.
My solution is to keep enough stuff in the boot that there’s always something to nestle the shopping in between.
e.g. mine currently contains: bike toolbox, dryrobe in bag for life, ikea bag, microwive-size plastic tub with emergency bike clothes in, bag for life with spare post-ride clothes in, nice stick my son found on a walk, 2×4 thick foam matting for standing on to get changed.
I put mine on the opposite side of the boot to the direction of most of the bends on the way home. Then really pin it hard round those bends so the shopping is definitely where I left it.
Thanks for some great recommendations here for what has been a tiresome issue. Just letting it fall over is not an option as the smell of egg can be horrendous. Bought a collapsible crate for the car.