The winning streak of German import Plein Ciel has continued at Caulfield with the talented horse maintaining an unbeaten run since arriving in Australia.

The Darren Weir-trained four-year-old, who races in the colours of Australian Bloodstock, made it four-straight wins since joining the stable of Victoria's premier trainer in Saturday's Swettenham Stud Summer Championships heat over 1800m.

Plien Ciel is rising through the grades in Melbourne and was sent out the $1.95 favourite after convincing performances at Warrnambool, Sandown and Caulfield.

Apprentice Ben Allen settled the favourite in the box seat and got him into the clear turning for home before quickly putting a couple of lengths on his rivals early in the straight.

Cool Chap closed the gap to three-quarters of a length on the line with Bondeiger the same margin away third.

"He's going really well," Weir said.

"Obviously he was racing inside them today and had to bustle his way out on the corner. Halfway up the straight it looked like he was going to run right away from them but the last 100 yards, it wouldn't have wanted to be much further or Cool Chap might have won.

"But all you can do is win and he's going in the right direction."

Weir believes there's still improvement to come.

"There's still a long way to go but hopefully he ends up in a nice race one day," Weir said.

"I'm not sure what we do now but there are some nice staying races coming up. I'm not sure whether we go there but obviously the Hobart Cup is an option for really good prize money. And a trip away wouldn't hurt him either, it would make him grow up a bit."

Plein Ciel was the first leg of a of a race-to-race double for Weir and Allen who combined for victory with Burning Front in the 1600m open handicap.