Is the country you wish to drive in covered, as not all policies cover every European country?
How many passengers are allowed in your vehicle? If you have a people carrier with you plus 5 family members it’s going to be tough to find out that your policy only covers 2 of you to be transported for your onward journey.
** Does it cover you for trips to a second home as some policies specifically exclude this?
Does it offer misfuelling cover, i.e. putting petrol in a diesel or vice versa. That's easier than you think in a foreign country, especially if you don't know the French word for Unleaded. (See Petrol Prices article here)
If your car can’t be fixed at the roadside does it offer onward travel cover?
Is it the car or the driver that’s covered, important if you drive more than one car?
Do they have English speaking phone operators?
Does it offer car hire while yours is being repaired?
Hotel accommodation paid for if you need an overnight stay while your car is being fixed?
Are you covered if the vehicle is vandalised?
Does it have caravan or trailer cover?
What, if any, are the limits they impose as to the number of days abroad you are covered for and the total value of repairs/garage bills they set as an upper limit?
How much are they willing to spend to get you and your passengers to your destination?
If the car has real problems that can’t be solved easily will they transport you and the car back to the UK? This type of clause could save you well over a thousand pounds if you needed this type of help.
This list of questions doesn't come close to covering every eventuality, so think to yourself what would be important to you in the event of a breakdown and check it out.