The Cars.com Redesign Index

It can cost up to $1 billion or more to develop a new or redesigned car, so sales success — and not just a little bit of it — matters. Determining which of those new cars hit the mark with consumers is no easy task. In the past three model years, significant redesigns averaged a 33% increase in year-over-year sales in the months after they were launched compared with their predecessors in the same period a year earlier. With numbers like that, most automakers could claim success with a redesign. But some cars rose above that lofty mark while others fell below. Which were the redesigns that car shoppers lined up for?

Cars.com crunched sales figures for 61 redesigns or introductions that replaced outgoing cars over the past four model years. We set a sales floor and grouped cars into three sales tiers — after all, a bit player can easily double its sales with a sharp redesign, but market saturation makes it harder for a popular model to do the same. We compared six months of sales after dealers ramped up inventory with the same time period from the year before. Finally, we also accounted for the growth in the overall auto market, meaning that if the whole market went up 10%, we assume that tide would have carried these redesigns as well.

Hyundai, Kia Mileage Mishap: How It Happened

How did Hyundai-Kia get its estimated mileage ratings so wrong that it had to offer reimbursement to some 900,000 owners? The truth is complicated, and it gets to the complexities of EPA testing.

Hyundai-Kia's Sung Hwan Cho told reporters this morning that it's "a very complex testing process." Cho heads the automaker's U.S. technical centers. He shed some light on the EPA tests, which lead to the city and highway fuel-economy figures on a new-car window sticker. A key part of the tests involve measuring the resistance of various systems, dubbed the "road load" by engineers: how a car's tires meet the pavement, how the vehicle's shape cuts through the air and how the drivetrain's moving parts work in tandem. Each area translates to fuel efficiency, or lack thereof.

"There are hundreds of different parameters that can affect this road load," Cho said. "Ambient temperature, wind speeds, atmospheric pressure."

Then there's a litany of variations within each test vehicle — how many miles are on it, the condition of the drivetrain, the tire wear. Finally, the test procedures themselves involve "which kind of regulation and guidance procedures you follow, and how you process the data, and how you calibrate your measurements," he said.

Somewhere in those variations, Hyundai-Kia went askew of EPA guidance. But exactly how much guidance exists is up in the air.

What to Do If You Own an Affected Hyundai, Kia

We reported this morning that Hyundai and Kia are revising gas mileage ratings for nearly 900,000 vehicles from the 2011 through 2013 model years — about a third of the cars sold by the affiliated Korean automakers over that range. 

What does it mean to you if you own one of the affected cars? We just got off the line with Hyundai and Kia officials, and here are some answers:

Cars.com's Mileage Tests of Hyundai and Kia Vehicles In Line With EPA Results

In the wake of today's news that Hyundai and Kia will reimburse owners for bad mileage estimates, we've compiled the results of our mileage tests from Shootouts and other challenges we've conducted over the past few years that involved the affected cars and SUVs.

In September 2011, we took the previously 40-mpg-rated Hyundai Elantra and pitted it against special "fuel-saving" trims from the competition designed to eke out a few mpgs more to hit that vaunted 40 mpg highway figure. The Elantra's new highway rating is 38 mpg, and its combined rating dropped to 32 mpg from 33.

Our results put the Hyundai in last place.

Hyundai, Kia to Pay 900,000 Owners for Bad MPG Estimates

Hyundai and Kia announced today they would reimburse owners of about 900,000 vehicles for misstated mileage ratings.

The news came after an investigation by the EPA into complaints from consumers that the two companies' mileage claims were inflated. As a result, the stated mpg ratings for 75 different trim levels over three model years will be changed, and window stickers of cars on sale will be replaced to reflect the new numbers.

Cars.com's Mileage Tests of Hyundai and Kia Vehicles In Line With EPA Results

The investigation began when the EPA received complaints from owners of the 2012 Hyundai Elantra compact sedan who said that they were not seeing gas mileage near the stated numbers. Once the EPA’s investigators confirmed a discrepancy, they broadened the audit to the rest of the vehicles.

Hyundai and Kia are owned by the same parent company in South Korea but operate separately in the U.S. Both have seen phenomenal growth in the past few years, not just because of improved styling and quality, but also for their exceptional fuel economy.

The changes affect the 2011-2013 model years with mileage ratings dropping from 1 to 6 mpg on the highway. Combined mileage ratings were more accurate with seven of the 43 Hyundai models and four of the 32 Kia models seeing no change in combined mileage after the audit. Twenty-four of the 43 Hyundais showed a difference of 1 mpg combined, while 11 of the 32 Kias were within 1 mpg of the original rating.

The company explained the error this way: "The fuel-economy rating discrepancies resulted from procedural errors during a process called 'coastdown' testing at the companies’ joint testing operations in Korea. Coastdown testing simulates aerodynamic drag, tire rolling resistance and drivetrain frictional losses and provides the technical data used to program the test dynamometers that generate EPA fuel economy ratings."

The two brands will announce a reimbursement program for current and former owners of the vehicles. A personalized debit card will be issued that will calculate the difference based on fuel prices and miles driven, plus 15% as a mea culpa from the automakers.

Will it be enough to satisfy consumers? That’s a question that will be asked nationwide as owners digest the news.

Below are the breakdowns of every vehicle impacted in the change, provided to Cars.com by Hyundai/Kia. We’ll have much more on this story as it develops throughout the day and coming weeks. If you have a question you’d like answered, leave it in the comments below or email us at editor@cars.com.

June's Fastest and Slowest Selling Cars

Seven all-new cars are off to a fast start. The Cadillac XTS hit dealerships just last month, but GM's flagship luxury car averaged just five days to sell. It tied the Hyundai Accent sedan and Subaru BRZ for June's fastest sellers. The nimble BRZ and its Scion twin, the FR-S, meanwhile, are taking just five and eight days to sell, respectively. Both cars hit dealerships in May.

We should see how many of each model sold in June when sales figures are announced later today.

Ford's redesigned 2013 Escape, Infiniti's new JX35 and two new Acuras — the ILX and redesigned RDX — also made June's Movers. The well-marketed Kia Soul, meanwhile, extended its tenure on the list to three months. Sales for the popular hatchback were up 22% through May. It's the most affordable car on the list, with a starting price (including destination) under $15,000.

May's Fastest and Slowest Selling Cars

The Toyota Prius may have left the Top 10 Best-Sellers last month, but shoppers still snapped up the latest additions to the Prius family: the Prius Plug-in and subcompact Prius c. Both have been among the fastest-selling cars since they hit Toyota dealerships earlier this spring.

Speaking of spring, the hottest one on record played well for Mercedes-Benz. The first full redesign in a decade for the iconic SL-Class roadster needed just eight days per car, on average, to sell. That car starts at $106,405 including destination.

Another droptop, the updated Ford Mustang convertible, sold fast, too, but its crosstown rival, the Chevrolet Camaro convertible, sat at Chevy dealers an average of 119 days. It joins a Losers list that remains mostly unchanged, with a scattering of posh — but slow-selling — nameplates.

2013 Hyundai Accent: What's Changed

• Most significant change: Heated side mirrors, remote keyless entry and air conditioning are now standard 
• Price change: $2,000 higher 
• On sale: now

Hyundai's popular subcompact gets more standard features for the 2013 model year, resulting in a big price increase for the base model.

All Accents now come with standard heated side mirrors, remote keyless entry, cloth inset door trim and air conditioning. Heated side mirrors are a new feature for 2013. Along with those upgrades, the base GLS with a manual transmission also gets satellite radio, a six-speaker stereo, USB port and body-colored door handles and mirrors.

Cars.com Family Reviews the 2012 Hyundai Accent

Can a compact car work as a family-hauler? If the family is on the small side and the car in question is a 2012 Hyundai Accent then Cars.com Family contributor Carrie Kim says the answer is yes. The Accent, which is available as a sedan or hatchback, holds five and has a surprisingly roomy interior. With its all-new sporty, fluid design, Carrie says the Accent is a looker, too.

2012 Hyundai Accent Review

2012 Hyundai Elantra, Accent Earn Four-Star NHTSA Ratings

The 2012 Hyundai Elantra and Accent received an overall rating of four out of five stars in the National Highway Traffic Safety Administration's crash-test rating system.

The Elantra's composite score is composed of a three-star frontal, four-star rollover and a five-star rating for the combined side pole and barrier tests. The side barrier test is an area where other vehicles have shown weakness with the safety agency's testing format. The side pole test simulates a 20-mph side-impact crash into a 10-inch-diameter pole or tree at a 75-degree angle just behind the A-pillar on the driver's side.

The Accent received four stars in frontal, rollover and combined side-impact tests, though NHTSA highlighted a particular safety concern with the Accent. During the side-impact barrier test, the left rear door intruded. The intrusion wasn't factored into the side-impact rating, however.

In crash tests by the Insurance Institute for Highway Safety, the 2012 Elantra received a Top Safety Pick award, meaning the vehicle received a Good rating (the agency's highest rating) in front, side, rear and roof-strength crash tests. The 2012 Accent had a Good rating in the roof-strength and the frontal crash tests, but an Acceptable rating in the side-impact test.