For a growing share of car buyers , paying for a vehicle is a seven-year commitment. A record 22.9% of financed new-car purchases in the first quarter involved loans of at least 84 months, according to new data from car shopping and research site Edmunds. That's up from 21.2% a year prior. A decade ago, it was 10%. The average amount financed for new cars also reached a record high, climbing to $43,899 in the first quarter, up from $41,473 a year earlier, Edmunds data shows. As the amount