BMW uses a Germanic alphanumeric naming system. Basically, models have a Series No. 1-8. (Note that series names are not hyphenated like Mercedes-Benz classes: 3 Series versus E-Class.) Larger odd numbered series means a bigger car. Even numbered series tend to be body style variants. The second two numbers in a model name indicate how big the engine is – they used to directly track engine displacement but no longer do. However, bigger number does equal bigger engine. The letter after the number (e.g. 340i) indicates what type of engine the car has. “X” models are SUVs. “Z” models are roadsters