Hi - it seems petrol is splashing out of the cap (just a tiny bit) when I go driving. I've tried various petrol caps but I can still smell the occasional smell of petrol when I turn a corner hard or brake hard. Is there any remedy for this?

Hi, guessing its in a early beetle?
Other than knowing its the correct cap for that tank and putting new cork / rubber seals in the cap ( was a problem with my old buggy) and make sure breather piping as crack free ( as this too could be your smell if it's not the cap itself)

check the seal under the fuel gauge sender

Maybe relevant, but i was in the same situation.

See, the stock breather pipe for my 69' goes from the filler neck, under the dash and back towards the tank near the passenger side then out under the front wheel arch area on the passenger side. When i'd fill the tank up, particularly when taking right turns i'd get a fuel odour, and upon investigation i culd see the breather pipe outlet near the wheel arch was damp. This 'seems' like the normal operation, but when full it allowed the excess to creep up and out and maybe loose a few mL's of petrol which didn't bother me but would certainly make a smell.

NOW! Where I am going, is the reason i could smell the fuel on the outside during the normal breather operation, was because of the bonnet seal and the seals for the indicators not being present (I believe). When you drive the cabin is often under vacuum (bernoulli's effect with windows down or the vacuum from the rear of the car passing into the engine bay and channels in the roof as you drive), and this causes the cabin to suck in air from the outside at the front into the bonnet, into the cabin (through the speaker grills, dash holes, demister vents etc). and thus, because i had no seals for my indicators, nor any bonnet seal, the fumes from the petrol breather at the front could pass into the cabin easily and get 'sucked in'.

After going nuts with silicone around the indicator wire holes and fitting a seal on the bonnet, it has cured it! Could possibly be the same cause for yours if there are unsealed openings from the bonnet into atmosphere. (This includes holes for the inspection plate covers).

check the small vent tube on the filler neck and the tube as well

if this is blocked it will pressurise the tank and force the fuel vapours past the cap gasket

Just to conclude this discussion - I am happy to let everyone know that after I unpinched the vapor slot in the fuel tank neck - the issue of vapor fumes has largely gone away.

I think the previous owner clamped the vapor slot thinking it would solve the fuel vapor problem. What he probably didn't realize was that fuel line that runs inside the car chassis spine tunnel had rusted and was leaking - I got Volkscare to fix that.

Most of the vapor fumes are noticable esp after I pump in the fuel. But it does occur in rare odd moments when I'm doing normal easy driving.

check sender seal, cap seal and breather pipe near the cap is attached.