BALTIMORE -- Marco Andretti points to improved results in street course races as the defining factor to  sitting fourth in the IZOD IndyCar Series championship. With the Grand Prix of Baltimore presented by SRT on deck, he has an opportunity to close the gap on front-runner Helio Castroneves.

Andretti, driving the No. 25 Dr Pepper car this weekend for Andretti Autosport, has recorded six top-10 finishes on seven temporary street circuits. The 75-lap race Sept. 1 on the 2.04-mile, 12-turn downtown Baltimore course is up first, followed by the Houston doubleheader Oct. 5-6.

"I've definitely been working on my street courses, which places like (Baltimore) have been the weaker part of my championship. But this year it's been the strongest part of my championship," said Andretti, who at Sonoma Raceway last weekend surpassed 17,000 career laps. "In the street courses, we're in it.

"This has been a tough one in the past, and I have this track marked as one where I want to show strong improvement, so I'd really like to see the Dr Pepper Chevy make the (Firestone) Fast Six so we can really give it our best shot come race day."

How he's fared on street courses this season:

Date

Place

Start

Positions gained/lost

March 24

St. Petersburg

7

4

April 21

Long Beach

25

18

May 5

Sao Paulo

10

7

June 1

Belle Isle 1

18

-2

June 2

Belle Isle 2

14

8

July 13

Toronto 1

10

6

July 14

Toronto 2

17

8

New primary sponsor on No. 55 car

Environmental Rail Solutions, a transportation logistics management company, will serve as primary sponsor on Tristan Vautier No. 55 car for the Grand Prix of Baltimore presented by SRT.

Vautier led every lap of the 2012 race on the way winning the race and two weeks later the Firestone Indy Lights championship.

"This is one of the rare street circuits that mixes slow corners, very fast corners, smooth asphalt, bumpy concrete and even a rail road crossing," Vautier said. "It takes so much focus to put a good lap together with all of those elements to overcome in Baltimore."

Of note

The Firestone Firehawk primary tires for Baltimore are the same as used at St. Petersburg, Long Beach, Detroit and Toronto. ... Charlie Kimball and Chip Ganassi Racing teammates Dixon and Franchitti all have participated in the Firestone Fast Six qualifying round past two races (Mid-Ohio, Sonoma). ... What's in a number? Takuma Sato, who started 13th at Sonoma in the No. 14 ABC Supply car for A.J. Foyt Racing, is 13th in the standings. He'll be in the 13th pit stall for Baltimore.