They still get way better gas mileage. They also don't cost $15,000 when the battery goes bad. I replaced my 12 year old prius battery myself in like two hours after buying a brand new $2,900 replacement from the Toyota dealership. Could have just bought and replaced the bad cell in it, but in a 12 year old battery I'd probably have another to replace within a year and just have to keep going in and replacing one after the other, which would be a pain.