The Croydon-based company's new trucks are both Arocs 1824L models with L ClassicSpace crewcabs and the 238bhp 7.7-litre straight-six engines driving through PowerShift 3 automated transmissions.
Their dropside bodies were mounted by Transport Enterprises, of Leicester.
"The company is growing strongly and needed additional vehicles to meet increased demand, so we felt the time was now right to buy our first new HGVs," states ASA managing director Lee Tolan.
"Mercedes ... trucks look smart on the road and have proved outstandingly reliable – our oldest is an 04-registered 18-tonne Atego, which has never given us a problem," he continues.
"Also, staying loyal to one marque makes life easier for our technician. He knows all about Mercedes-Benz products so it made sense to stick with them."
The vehicles, which have been acquired through Mercedes-Benz Financial Services, are being supported by supplying dealer Rossetts Commercials.