Wow, I forgot about this post.
I'm interested if your child has adhd, but I'd love to hear from parents of non-adhd kids as well, because I'm just wondering if the majority of kids really can get their homework over with in the amount of time suggested by the learning experts.
My daughter is thirteen and has adhd. My son is a squirrelly nine years old. They both experienced the same thing: when 'real' homework was first assigned in 1st grade, they both had a dreadful time sitting down and just doing it. Typically the teachers said they had about 20 minutes of homework nightly (first grade). I remember my jaw dropped the first time I read that. They both needed
hours to do it, with a whole lot of reminding, nagging, cajoling, bribing and long breaks. I finally discovered that if I sat right next whichever child, follow along, remind them to get back on track when they wander off, and help them when they get mired down, the whole thing was so much less painful. And they were done in half the time.
I've found that they've been able to focus longer and sit and do homework for greater lengths of time as they've gotten older. Obviously. I think I'm mentioning this to reassure myself that progress has been made!

StartingtoCrunch, your daughter can focus on homework in the car? She doesn't get distracted by everything along the way? Maybe gymnastics is a motivator?
Chiromamma, my daughter is similar. She's severely weighted towards language arts. Math is horrible for her. She started on adhd meds at the end of last school year and had a math tutor over the summer. It's been a real help for her.
How to encourage reading: Read to him every night. Pick a book that he'd enjoy hearing and you'd enjoy reading and read a chapter every night. I cannot stress enough how helpful this is. It will increase his vocabulary and comprehension and he'll simply love it. Choose a book that's more complex and challenging than he can currently read himself, but will also capture his interest.
My sister's son is not a fast reader. He's 23 y.o. now and a college graduate. She said she read to him up through middle school simply so he'd be familiar with some great stories that he wouldn't have bothered to read. It increased his cultural vocabulary. Maybe he didn't feel like reading the Wizard of Oz, but he was happy to hear it read to him and now he's familiar with the story.
Do you read for pleasure? My husband and I both read almost nightly. The kids are aware of it and reading for fun is just part of their nature now.
I'm currently reading Sea of Monsters from the Percy Jackson series to ds. It's very convenient that each chapter takes about 30 minutes to read. To himself ds is reading Diary of a Wimpy Kid (again) and the Indispensable Calvin and Hobbs (again).

His dad also gets him a subscription to kids Spiderman and kids Teen Titans comics. And Santa gave him a subscription to National Geographic Kids last year, and he's thrilled every time HIS magazine shows up in the mail.