Use her to get a car

Matt and his imp got off at the mall, walking toward a car dealer.
"Alright, so lets make my life a little better then. I need a car, I can afford something cheap." Matt said.
"Oh, rigging a business deal, I can work with that." giggled the little imp. "I do one of my favorite spells, make them have difficulty lying and add a desire to help you."
Walking in the dealership, he was quickly matched with a salesman. And sure enough, he couldn't lie, he broke down to the lowest possible price on a nice 2010 truck, and gave him amazing financing. Matt felt like he had won the lottery. All the while the imp fluttered around, occasionally making gestures at the salesman.
Driving out of the lot, Matt felt like a million bucks.
The imp seemed a little tired after, but she was quite chipper, complementing in her sing-song voice as Matt as they drove.