If you let your car insurance lapse and you get pulled over then you'll likely either get a fine or get your vehicle towed away due to not having car insurance due to it being lapsed.
Also if you get into an auto accident and you have let your auto insurance lapse then you could be fined and sued by the other driver whether the auto accident is your fault or not.
If you let your auto insurance policy lapse then you should not drive your vehicle because the risk is just too high and you can lose your vehicle and/or get fined.