Alice Siu of Volvo Cars Hong Kong says the sound system in the new variable-roof Volvo C70 (below) offers 'concert hall' sound when the metal roof is up, or become 'an open-air arena' when it's down. That's a big claim in Hong Kong, firstly because some of our road surfaces can be noisy, and secondly because the turbo-charged, 2,521cc C70 has lots of whoosh, with a top speed of 235km/h and a 0-100km/h sprint in eight seconds. 'A car represents one of the most difficult challenges for an audio engineer,' Siu says. 'The passenger compartment has irregular shapes. It's a mixture of hard and soft materials, and has considerable variation in surface structures.' And the road surface changes as you drive. 'In a convertible, the situation is further complicated by the fact that the roof is sometimes up and sometimes down,' Siu says. So, Volvo's Digital Signal Processing technology adapts the sound to the passenger compartment's design. 'One important ingredient in this system is a digital 139W amplifier that is considerably more efficient than its analogue equivalent,' Siu says. The sound can be adapted to the driving situation. 'Not only the volume, but also the tone settings are adjusted automatically, in line with the car's speed. The sound is also adjusted automatically when the roof is up or down to ensure the listener gets the same sound.' There are three sound-system options for the new Volvo C70: a 'performance' 4x20W amp and four speakers; 'high performance' with 4x40W amp and eight speakers; and 'premium sound', which has a 5x130W digital amp, Dolby Pro Logic II Surround and up to 14 speakers, including optional dual subwoofers and integrated amps. All in, you could whack Led Zeppelin's Black Dog at almost 1kW, which we think is dangerously loud. But the car stereo system to beat is the Lexus SC430's Levinson system, which passed our Yundi Li test in Mid-Levels, recently. You could hear every kerplunk of Chopin's piano sonata, even though some might say the SC430 is more Richard Clayderman territory. Lend your ears to both cars. The Mad Dog Motor Cycle Club (left) starts its Third Poker Run in Granville Square, Tsim Sha Tsui, at 11am on May 14. Bring $100 for entry and enough gas for 100km, say organisers. Also, the MG Owners' Club holds its splendid annual concourse at Taikoo Place at 1pm on May 21. To enter your MG, tel: 2966 7845. Finally, next Sunday is Mother's Day. So, if you have any 'motoring with mother' stories, plan to take the old dear for a drive next weekend, or would just like to enter her in our back-seat driver awards, e-mail email@example.com .