Four years after landing an engineering job with Sunoco, Ian MacKinnon, 26, is eager to make his savings work for him. By living frugally, the former college athlete has paid off his student loans and amassed $25,000 in a savings account. MacKinnon also contributes 15 percent to 20 percent of his paycheck to his company’s 401(k) and qualifies for his employer’s 5 percent match. Despite this cushion, MacKinnon says his strategy needs a jolt. He insists that at least $10,000 remain in the bank, but he’s eager to earn higher returns on the rest of his money. Still, he doesn’t want to put all of the remaining $15,000 at risk. He anticipates buying a house and a new car and going to graduate school, but he doesn’t expect to take on any of those obligations in the next five years.