Wiktionary
n. (context UK NZ English) A young man who drives recklessly fast, especially one who participates in gatherings of car-culture enthusiasts and/or in illegal street racing.
Wikipedia
A boy racer is a motorist who drives an automobile that has been modified with aftermarket body kits, audio system and exhaust system, usually in an unlawful manner. It can also mean a compact sporty coupe that is heavily modified for racing. Wealthier motorists who drive sports cars, or those with costly modifications, often seek to distance themselves from the culture. Responses to the boy racer phenomenon range from laws prohibiting cosmetic modifications to vehicles such as decorative lighting and window tint, restrictions on recreational driving ("cruising"), to vandalism such as spraying expanding foam into cars with loud "big-bore" exhaust tips to stop such cars driving around emitting loud droning noises.
Usage examples of "boy racer".
Oakes got in a swipe before he was propelled back into the road, where the boy racer, oblivious to the fight, radio on full-blast and his girl with her arm around him, was showing off his carps acceleration from a flat start.