My Bugbear is the Hidden Costs of Insurance Excess fees
Renting a car can be a pain but surely the car rental companies could make it a bit less painful
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such as the excess reduction policies of the car rental companies. Any frequent renter will know the feeling I am talking about when "that" question comes from behind the rental desk;

"Do you want to reduce your car rental excess on your car rental Mr Smith?" This can cost from $22 to 27 dollars to reduce your excess from $3300 down to $300. If you don't take it up your trip can become a worry and at worst a nightmare if you have an accident. "Have a pleasant trip Mr Jones ( We hope our rental car is not stolen or you have a bit of a bingle or it could cost you a heaps!)"    Here is more info on car hire excess cover  *Wikipedia on car rental excess insurance

"There is however, another insurance alternative that can reduce these risks and costs. Specialist excess protection insurance from a number of other insurers can offer excess protection, much broader coverage and may include cover for those areas often excluded. In the event that the vehicle is damaged or stolen, the rental company will charge your credit card for the excess amount and you then claim for reimbursement on your vehicle hire excess protection policy".

TRAVEL INSURANCE
Another alternative is to use travel insureance. SImply take out travel insurance for your rental car. The restrictions with taking travel Insurance is that there is a minimum number of days required, but great for more than a 4 day rental.
1Cover and Travel Insurance Direct offer good rates.