This paper describes recent improvements in the design of model solar racers based on experience with first-year engineering and middle school students. With both audiences, the main educational goal is to introduce students to engineering in a fun way. Several modifications have been added to improve our program relative to the national Junior Solar Sprint, including 1) less expensive, more durable solar cells, 2) a different DC motor that matches the lower power output and higher array voltage possible with the new cells, and 3) an additional race powered by rechargeable batteries. Another distinguishing feature of our effort is the combination of field experience from the middle school and engineering analysis with the first-year engineering students. These efforts inform one another and have resulted in an enhanced understanding of the performance characteristics and tradeoffs in the design process. We have been able to build an analytical model that accounts for the possible variables affected by the design. These include gear ratio, friction, car mass, drag coefficient, frontal area, array wiring, and solar intensity. We have also developed simple tests to determine solar and motor performance.