Motorists are being cautioned that they, along with their passengers, must adhere to five crucial rules or risk incurring fines of as much as £5,000 and potentially face jail time. A particular habit that might seem harmless in most circumstances could lead to serious consequences when carried out inside a car. Car specialist Darren Miller from BigWantsYourCar.com has sounded the alarm, indicating that despite common knowledge around certain dos and don’ts, people often dismiss them as trivial and carry on regardless. The habit in question? Smoking in the presence of minors within your vehicle is strictly off-limits unless all occupants are over 18. In the first warning, Darren cautioned: "Smoking in vehicles with passengers under 18 is another situation where fines may apply, amounting to up to £50 for both the driver and the smoker. Beyond the financial implications, the health risks to children from exposure to cigarette smoke in enclosed spaces highlight the seriousness of this offence." Here's a rundown of the other four essential practices drivers must abandon immediately, reports the Express . Wearing a seatbelt is widely understood as a basic safety rule, but are you aware of the consequences if you or a passenger fails to comply? The expert highlighted that drivers can be hit with a £100 fine and receive 3 penalty points on their licence. Additionally, the expert stresses that it's the driver's legal responsibility to ensure all children under 14 are properly belted, with fines reaching up to £500 per child for non-compliance. Darren explained: "Exceeding the designated passenger capacity of a vehicle not only risks safety but can also lead to fines of up to £100 for the driver or, in more serious cases, a two-year prison sentence. The potential distractions from overcrowded vehicles increase the risks of accidents, making it important for drivers to keep to passenger limits." Regarding mobile phone use by passengers, Darren highlighted: "Passenger use of mobile phones, especially when supervising a learner driver, can also attract fines of up to £1,000 for the driver, along with six penalty points on their licence. Drivers must always focus on the road and ensure passengers follow legal restrictions on phone use while in the vehicle." Pet owners are being cautioned about the dangers of travelling with unrestrained animals, as they can become serious distractions and pose safety risks on the road. The motoring expert warned that failing to properly secure pets while driving could lead to hefty penalties, with fines reaching up to £5,000.