Martin Lewis says little-known device could cut car insurance bills for some driversCar insurance is one of the biggest financial hurdles for teenagers and those in their 20s who are hitting the roadView Image Martin Lewis has offered advice that could help some drivers cut their car insurance bills (Image: Getty)Martin Lewis has offered advice that could help some drivers save money on their car insurance bills. ‌The Money Saving Expert dedicated a portion of Tuesday evening's special edition of The Martin Lewis Money Show to tackling car insurance concerns. ‌"I'd be looking, if I was in your position - do you know what a black box is, a black box insurance?" ‌Martin Lewis continued the conversation, asking: "Is it based on how you drive or the time you drive" to which the young motorist replied "How I drive." Black box insurance, also known as telematics cover, works by tracking driving habits including speed, braking patterns and journey times.