With two of the segment’s highest-selling models going through redesigns for the 2012 model year, NADA Used Car Guide opted to take a closer look into retained values for compact luxury units.

Analysts just placed used values on the 2012 version of the BMW’s 3 Series and Mercedes-Benz’s C Class for the first time and determined which model stacked up best against its segment competition, including the Acura TL, Audi A4, Cadillac CTS, Infiniti G37 and the Lexus IS250.

To arrive at which model retained the most value, NADA UCG used a typically equipped MSRP that included automatic transmission and power sunroof, as well as those packages most often found on a given model such as convenience or style packages.

The table below highlighted this built MSRP along with average trade-in values from August’s edition of the Official Used Car Guide. The table also contains a used value retention figure, which was created by dividing August’s trade-in value by our typically equipped MSRP.

Since analysts said the C Class’ retention is typically right around the average for the segment, NADA UCG said that Mercedes-Benz’s current leading rate suggests a couple of factors.

“First, the sedan’s more masculine restyle and interior refinements have been very well received,” executive automotive analyst Jonathan Banks began. “On the inside, Mercedes gutted the 2011 model year interior and refitted it with improved materials and design, now more closely resembling higher end models in their lineup. Second, the new, 1.8L turbocharged inline four cylinder, 201 horsepower engine placed in the C250 is more fuel-efficient than the previous 3.0L V6.”

Like the C Class, analysts noted the 2012 BMW 328i sedan was also revised for the 2012 model year, but Banks surmised that changes — at least those that can be seen — were a bit more subtle.

“On the exterior, BMW’s designers used a lighter touch by rounding off corners, but the most significant change to the sheet metal was probably the extension of the headlights to BMW’s trademark kidney grille,” Banks highlighted. “The 328i was also given a new turbocharged engine that displaces 2.0L and produces 240 horsepower.

“While the BMW gets the nod in the power department and the initial retention for the 3 Series has increased relative to last year’s outgoing model, the subdued exterior changes don’t appear to have had quite the same effect as those for Mercedes’ compact,” he continued.

Looking back to last year at the initial retention of 2011 models, analysts determined the 3 Series and the C Class came in with retention figures of 81.9 percent and 75.3 percent, respectively. These levels put them at first and fifth place out of seven models in the overall segment pecking order.

“When compared to this year, we see that retention has improved by a dramatic 16 points for the C Class, and by five points for the 3 Series,” Banks pointed out

For this year, NADA UCG said the rest of the 2012 model-year crop is scoring much lower in relation to value retention.

“The IS250, A4 Premium Quattro, TL, CTS, and G37 are all well back of the aforementioned models, but this isn’t surprising considering that the remaining sedans in group have been around in their current form for quite some time now,” Banks explained.

“That being said, retention for the A4, IS250, and TL remains quite strong, which is worth noting as each vehicle was last redesigned for the 2009, 2006 and 2009 model years, respectively,” Banks continued. “The retention for these models at an advanced age is a good example of how design (Audi) and quality (Lexus, Acura) elevate awareness and demand.”

In regard to average incentive spending, NADA UCG noted that from January through June of this year incentive offerings on the C250 ($2,760) and 328i ($3,182) were actually the lowest of the group.

“This is no coincidence, as lower incentive spending helps strengthen used-value retention,” Banks emphasized. “With lower incentive spending the actual new transaction prices tend to trend higher as well.

“The Cadillac CTS and Infiniti G37 are good examples of what can happen when awareness, design, or age — or combinations of the three — are at a disadvantage,” he cautioned. “In these cases, demand is softer and incentive spending usually increases well beyond the market average — ultimately, used prices suffer."

Through June of this year, analysts determined average incentive spending on the CTS was approximately $4,694 per vehicle. For the G37, it was $5,921. They also mentioned average days’ supply for the CTS and G37 was also the worst in the segment at 119 for the CTS and 96 for the G37.

“Not coincidentally, both these models currently have the poorest value retention,” Banks said.

“The new BMW 3 Series and Mercedes C Class — and the older Audi A4, Lexus IS, and Acura TL — demonstrate how important design is in this age of increased parity and how well received product updates are narrowing the degree of separation between models within this competitive set,” he concluded.