Which brand/model? There were some older SUVs that had a mild hybrid system that was basically using the starter motor to get the car rolling. It only resulted

Which brand/model? There were some older SUVs that had a mild hybrid system that was basically using the starter motor to get the car rolling. It only resulted in a very small increase in gas mileage on a vehicle that burned a lot of gasoline. Those were no more reliable than the ICEV versions.