Got any plans for this weekend? Catching up with friends, spending time with the family, or planning on spoiling yourself? Chances are you'll do one, if not all, of the above, and it's likely your car will play a vital role.

Imagine the impact on your lifestyle if your freedom machine is one of the 20,000 that will be stolen or the 45,000 involved in a crash this year. Still, it's lucky you've got car insurance, right? But do you know what you're covered for?

Did you read the fine print when you took out the insurance policy? Scary fact one: one in 10 vehicles on Victorian roads are uninsured, and if you're one of the 20 per cent with only third-party property coverage, you're gambling with your second-most expensive possession.

In Victoria, only "third-party personal" insurance is compulsory. It insures you for injuries you cause to other road users but not to their property or yours. After that, it's up to you to choose between the three main levels of car insurance: third-party property; third-party property, fire and theft; and comprehensive.

Third-party property covers any damage your vehicle causes to other peoples' property, but there is a limit to how much an insurance company will pay out - in AAMI's case, it's $20 million - so no crashing into solid-gold Rolls-Royces. Damage to your own vehicle is not covered, though some insurance companies will contribute a nominal amount ($3000) towards damage to your car - if the accident wasn't your fault, the other driver is uninsured and you are able to identify the driver. And that $3000 must also cover the cost of towing, if needed.

Adding fire and theft coverage increases your premium and your cover, but most insurance companies will only pay out $5000 even if your vehicle is destroyed by fire or theft. It does not cover items in your car such as mobile phones, CD players or briefcases.

"We get letters from people all the time saying third-party property should be made compulsory," says Susan Allen, RACV's general manager, insurance. The RACV is Victoria's largest car insurance company, with a 40 per cent share of the 2.2 million Victorians that have car insurance.

"When someone's spent their heard-earned income on a car and an uninsured third party writes it off, it's tough," Ms Allen says. "We try to help by giving them the standard template of a legal letter to send, but there's little we can do beyond that. And, of course, they're not insured for damage to their vehicle through us, only for damage to another."

Thankfully, crashes involving uninsured vehicles are not too frequent - and you've got comprehensive insurance, right? The dictionary may define comprehensive as "complete coverage", but it more closely resembles a carefully crafted blanket of Swiss cheese.

Are your tyres bald? Or maybe you're driving a few kilometres over the speed limit. Had one or two drinks at a family barbecue, could be over 0.05 but should be fine to drive? Scary fact two: Car insurance doesn't cover you if you break the law or your car is not roadworthy, even if the crash wasn't your fault.

That last one's a double whammy for Victoria, which - unlike some states, including NSW - does not have compulsory annual roadworthy checks and does little to ensure cars are roadworthy. Victorians are only required to ensure their vehicles are roadworthy when selling, so if the average Victorian replaces their car every seven years, when was the last time it was given a once-over? Technically, a blown brake bulb is enough to void some insurance contracts.

OK, you always abide by the law, but how closely did you study the fine print the last time you renewed your policy? Scary fact three: 60 per cent of car insurance complaints arise because people aren't as covered as they thought. In effect, you are signing a new contract with the car insurer every 12 months, and it may not have the same conditions as the previous period.

Scary fact number four (and this one's a beauty): if, because your car is stolen or written off, you need to buy a new car, you'll lose the balance of your premium on the previous car and will need to stump up the full premium for the replacement vehicle. Imagine the financial impact this could have if you only just renewed your policy. In some cases, this, along with forking out the $400-$1500 insurance excess, could put you thousands of dollars out of pocket.

The list of scary insurance facts is almost as long as a teenager's book of excuses. Teaching little Johnny to drive and forgot to inform the insurance company? Not covered.

Selling your car privately? The car is not insured while a prospective customer takes it for a test drive.

Thinking of doing a defensive driving course? Your car is not covered if the course takes place on a closed circuit or racetrack of any kind.

And don't think of taking a scenic drive through any war zones, because your car's not covered for war damage. It's also not covered if damaged in a riot or looting spree. Floods? Not covered in the first few days of your policy.

Enough, already. Lesson learnt - must pay more attention to car insurance. The best time to start is before you buy the car; that's when you can do the most to shave hundreds of dollars off your insurance costs without compromising cover.