"I'd have to say that he's a good driver but sometimes he sits right up someone's bum like he's drafting [slipstreaming] or something. He's got great reaction but the others don't."
Dixon is in New Zealand this week as the guest of honour at a charity lunch for CanTeen on Friday, and at the Big Boys Toys event for a Q&A session on Saturday.
Dixon, 34, has been competing in the IndyCar event since 2003, winning three titles and an Indianapolis 500.
The couple live full time in the US with their two daughters, 5-year-old Poppy and 3-year-old Tilly.
Emma said that when driving on the roads in America her husband would rather be in command and control than relaxing in the passenger seat of the family's Audi Q7 or her Range Rover.
"I'd rather get on a bus. I've also got a 50cc scooter and I'd rather potter around on that," laughed Emma. "He's a complete backseat driver.
"To be honest, I don't actually drive that much. While I'm getting the kids ready and putting my shoes on he's already sitting in the driver's seat. I get tired if I drive more than two hours, while he can go eight hours or more - the boy was born to drive."
The IndyCar season begins in March and ends in August, with 17 races in the US, Canada and Brazil. Out of season, Dixon has a full schedule of sponsor and team commitments, so time at home is precious. "I miss him terribly during the season and when he's at home I really appreciate him and our time together," said Emma.
"Sometimes during the off-season, though, I'll ask him when he starts testing again because he gets itchy feet and just wants to be back in the [race] car."
Emma is herself a track star, but it's the running track, rather than race track. Before she met Dixon, she represented Wales as Emma Davies in the 800m race at the 2002 Commonwealth Games in Manchester.
Exclusive interview
Scott Dixon is a New Zealand motoring legend - but was still made to resit a test to renew his driving licence. In an exclusive interview with the Herald, he said he was taken aback recently when told he would need to resit a test to renew his licence as he had too many speeding points to get an automatic renewal.
"I have no idea how I passed, but I tell you I was sweating at the time."