Availability varies. Enrollment discount applies during data collection; final discount is calculated on driving behavior and could be zero. Discounts do not apply to all coverage elements; actual savings vary by state, coverage selections, rating factors and policy changes. Final discount applies at the next policy renewal and remains until drivers or vehicles on the policy change.
Yes, you surely can avail the NCB if you change your insurance provider at the time of renewing the policy. All you would need to do is producing a proof of the earned NCB from your current insurance provider. You can produce the original copy of your expiring policy and a certification that you haven’t filed any claim for the (expiring) insurance plan. A renewal notice or a letter stating that you’re entitled to the NCB from your previous insurance provider can be a proof for this.
Any car insurance comparison tool you look at should have your state’s minimum car insurance requirements pre-loaded into its options. States requiring PIP or medpay are generally referred to as “no-fault” states, meaning that when injuries occur, each driver in a crash makes a claim with their own insurance company to pay for them. Beyond the PIP or medpay limit, the at-fault driver’s liability insurance kicks in to cover the rest.
Cents Per Mile Now (1986) advocates classified odometer-mile rates, a type of usage-based insurance. After the company's risk factors have been applied, and the customer has accepted the per-mile rate offered, then customers buy prepaid miles of insurance protection as needed, like buying gallons of gasoline (litres of petrol). Insurance automatically ends when the odometer limit (recorded on the car's insurance ID card) is reached, unless more distance is bought. Customers keep track of miles on their own odometer to know when to buy more. The company does no after-the-fact billing of the customer, and the customer doesn't have to estimate a "future annual mileage" figure for the company to obtain a discount. In the event of a traffic stop, an officer could easily verify that the insurance is current, by comparing the figure on the insurance card to that on the odometer.
Driving without the necessary insurance for that vehicle is an offence that can be prosecuted by the police and fines range from 841 to 3,287 euros. Police forces also have the power to seize a vehicle that does not have the necessary insurance in place, until the owner of the vehicle pays a fine and signs a new insurance policy. The same provision is applied when the vehicle is standing on a public road.
Providers can also offer sub-divisions of auto repair insurance. There is standard repair insurance which covers the wear and tear of vehicles, and naturally occurring breakdowns. Some companies will only offer mechanical breakdown insurance, which only covers repairs necessary when breakable parts need to be fixed or replaced. These parts include transmissions, oil pumps, pistons, timing gears, flywheels, valves, axles and joints. 
Vehicles kept in the UK must now be continuously insured unless a Statutory Off Road Notification (SORN) has been formally submitted. This requirement arose following a change in the law in June 2011 when a regulation known as Continuous Insurance Enforcement (CIE) came into force. The effect of this was that in the UK a vehicle that is not declared SORN, must have a valid insurance policy in force whether or not it is kept on public roads and whether or not it is driven.
Widespread use of the motor car began after the First World War in urban areas. Cars were relatively fast and dangerous by that stage, yet there was still no compulsory form of car insurance anywhere in the world. This meant that injured victims would seldom get any compensation in an accident, and drivers often faced considerable costs for damage to their car and property.