The 32-year-old had his second test drive for Mercedes-Benz at Estoril, Portugal, and was positive about his experience.
"I wouldn't be driving here if the DTM car wasn't a great deal of fun for me," Schumacher told German tabloid Bild.
"And, it goes without saying, if I didn't enjoy it, I wouldn't seriously consider racing in DTM."
Mercedes keen on Ralf
17/01/2008 AT 14:27
Having won six Grand Prix in his 11 years in Formula One, Schumacher had his first test drive for Mercedes in mid-January and now wants to make sure he puts the experience to good use.
"Now, I want to use every minute for getting to know the car," said Schumacher, whose Toyota contract expired at the end of last season.
"After all, I'm new to the DTM business and would have to get to know everything and used to racing the car."
And after such a positive start, Mercedes bosses in Stuttgart are expecting an answer by the end of the month.
"I assume a decision will come in February," Mercedes racing boss Norbert Haug told German agency SID.
"If Ralf is interested then we can certainly work together."
But as the brother of seven-times world champion, Schumacher's name alone will not guarantee success and Haug warns against expecting too much from the German.
"I'd recommend Ralf has a C-class model from 2007, which is better for learning and takes away some of the pressure."
Haug insists it is imperative Schumacher gets used to the different handling of the type of cars used in DTM racing.
"Formula One and DTM are entirely different, as Mika Hakkinen found out," said the Mercedes boss.
Twice world champion Hakkinen spent three years in DTM and struggled to make an impact, finally quitting at the end of the 2007 season and Haug insists Schumacher is not seen as a replacement star.
"We aren't looking for a new Hakkinen and we aren't interested in signing Ralf just for the headlines."