NEW YORK (TheStreet) -- Sales at major automakers are up and down. General Motors (GM) sold 3% more cars in May 2015 than in May of last year, while Ford (F) sold 1.3% fewer cars in the same period, and Fiat Chrysler (FCAU) sold 4% more cars over the same period.

U.S. auto industry sales may reach the elusive 17 million cars in 2015 based on sales through May; quite a remarkable turnaround since the recent recession, when just 5.7 million cars were sold in 2009. A brightening job outlook, relatively cheap gas prices, and moderate price increases for new cars may contribute to making 2015 the best year in car sales since 2001.

So, what are the best automobile manufacturers should be buying? Here are the top six, according to TheStreet Ratings,TheStreet's proprietary ratings tool.

TheStreet Ratings projects a stock's total return potential over a 12-month period including both price appreciation and dividends. Based on 32 major data points, TheStreet Ratings uses a quantitative approach to rating over 4,300 stocks to predict return potential for the next year. The model is both objective, using elements such as volatility of past operating revenues, financial strength, and company cash flows, and subjective, including expected equities market returns, future interest rates, implied industry outlook and forecasted company earnings.

Buying an S&P 500 stock that TheStreet Ratings rated a buy yielded a 16.56% return in 2014 beating the S&P 500 Total Return Index by 304 basis points. Buying a Russell 2000 stock that TheStreet Ratings rated a buy yielded a 9.5% return in 2014, beating the Russell 2000 index, including dividends reinvested, by 460 basis points last year.

Check out which automobile manufacturers made the list. And when you're done, be sure to read about which volatile aerospace and defense stocks to buy now. Year-to-date returns are based on June 23, 2015, closing prices. The highest-rated stock appears last.

WGO ChartWGO data by YCharts
6. Winnebago Industries, Inc. (WGO)

Rating: Buy, B
Market Cap: $590 million
Year-to-date return: -6.8%

Winnebago Industries, Inc. manufactures and sells recreation vehicles primarily for use in leisure travel and outdoor recreation activities.

"We rate WINNEBAGO INDUSTRIES (WGO) a BUY. This is driven by several positive factors, which we believe should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks we cover. The company's strengths can be seen in multiple areas, such as its revenue growth, largely solid financial position with reasonable debt levels by most measures, good cash flow from operations and notable return on equity. We feel its strengths outweigh the fact that the company has had lackluster performance in the stock itself."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • WGO's revenue growth has slightly outpaced the industry average of 6.9%. Since the same quarter one year prior, revenues slightly increased by 2.5%. This growth in revenue does not appear to have trickled down to the company's bottom line, displayed by a decline in earnings per share.
  • WGO has no debt to speak of therefore resulting in a debt-to-equity ratio of zero, which we consider to be a relatively favorable sign. Along with the favorable debt-to-equity ratio, the company maintains an adequate quick ratio of 1.09, which illustrates the ability to avoid short-term cash problems.
  • Net operating cash flow has increased to -$14.43 million or 18.17% when compared to the same quarter last year. Despite an increase in cash flow, WINNEBAGO INDUSTRIES's average is still marginally south of the industry average growth rate of 23.55%.
  • The company's current return on equity has slightly decreased from the same quarter one year prior. This implies a minor weakness in the organization. In comparison to the other companies in the Automobiles industry and the overall market, WINNEBAGO INDUSTRIES's return on equity significantly exceeds that of the industry average and is above that of the S&P 500.
  • WINNEBAGO INDUSTRIES's earnings per share declined by 14.3% in the most recent quarter compared to the same quarter a year ago. This company has reported somewhat volatile earnings recently. We feel it is likely to report a decline in earnings in the coming year. During the past fiscal year, WINNEBAGO INDUSTRIES increased its bottom line by earning $1.65 versus $1.13 in the prior year. For the next year, the market is expecting a contraction of 4.2% in earnings ($1.58 versus $1.65).

GM ChartGM data by YCharts
5. General Motors Company (GM)

Rating: Buy, B
Market Cap: $58.3 billion
Year-to-date return: 4%

General Motors Company designs, builds, and sells cars, crossovers, trucks, and automobile parts worldwide. It operates through GM North America, GM Europe, GM International Operations, GM South America, and GM Financial segments.

"We rate GENERAL MOTORS CO (GM) a BUY. This is driven by multiple strengths, which we believe should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks we cover. The company's strengths can be seen in multiple areas, such as its increase in net income, impressive record of earnings per share growth, notable return on equity and largely solid financial position with reasonable debt levels by most measures. We feel its strengths outweigh the fact that the company has had lackluster performance in the stock itself."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • The net income growth from the same quarter one year ago has significantly exceeded that of the S&P 500 and the Automobiles industry. The net income increased by 343.7% when compared to the same quarter one year prior, rising from $213.00 million to $945.00 million.
  • GENERAL MOTORS CO reported significant earnings per share improvement in the most recent quarter compared to the same quarter a year ago. This company has reported somewhat volatile earnings recently. But, we feel it is poised for EPS growth in the coming year. During the past fiscal year, GENERAL MOTORS CO reported lower earnings of $1.64 versus $2.35 in the prior year. This year, the market expects an improvement in earnings ($4.48 versus $1.64).
  • The return on equity has improved slightly when compared to the same quarter one year prior. This can be construed as a modest strength in the organization. Compared to other companies in the Automobiles industry and the overall market on the basis of return on equity, GENERAL MOTORS CO has outperformed in comparison with the industry average, but has underperformed when compared to that of the S&P 500.
  • Regardless of the drop in revenue, the company managed to outperform against the industry average of 6.9%. Since the same quarter one year prior, revenues slightly dropped by 4.5%. The declining revenue has not hurt the company's bottom line, with increasing earnings per share.
  • Even though the current debt-to-equity ratio is 1.33, it is still below the industry average, suggesting that this level of debt is acceptable within the Automobiles industry. Regardless of the somewhat mixed results with the debt-to-equity ratio, the company's quick ratio of 0.79 is weak.

HMC ChartHMC data by YCharts
4. Honda Motor Co., Ltd. (HMC)

Rating: Buy, B
Market Cap: $60.4 billion
Year-to-date return: 13.5%

Honda Motor Co., Ltd. manufactures and sells motorcycles, automobiles, and power products. It operates through four segments: Motorcycle Business, Automobile Business, Financial Services Business, and Power Product and Other Businesses.

"We rate HONDA MOTOR CO LTD (HMC) a BUY. This is driven by a number of strengths, which we believe should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks we cover. The company's strengths can be seen in multiple areas, such as its good cash flow from operations and largely solid financial position with reasonable debt levels by most measures. We feel its strengths outweigh the fact that the company has had lackluster performance in the stock itself."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • Net operating cash flow has increased to $4,169.55 million or 13.75% when compared to the same quarter last year. Despite an increase in cash flow, HONDA MOTOR CO LTD's average is still marginally south of the industry average growth rate of 23.55%.
  • HONDA MOTOR CO LTD has experienced a steep decline in earnings per share in the most recent quarter in comparison to its performance from the same quarter a year ago. The company has suffered a declining pattern of earnings per share over the past year. However, we anticipate this trend reversing over the coming year. During the past fiscal year, HONDA MOTOR CO LTD reported lower earnings of $2.42 versus $3.10 in the prior year. This year, the market expects an improvement in earnings ($2.65 versus $2.42).
  • HMC, with its decline in revenue, slightly underperformed the industry average of 6.9%. Since the same quarter one year prior, revenues fell by 12.6%. Weakness in the company's revenue seems to have hurt the bottom line, decreasing earnings per share.
  • Even though the current debt-to-equity ratio is 1.01, it is still below the industry average, suggesting that this level of debt is acceptable within the Automobiles industry. Regardless of the somewhat mixed results with the debt-to-equity ratio, the company's quick ratio of 0.82 is weak.
  • The company's current return on equity has slightly decreased from the same quarter one year prior. This implies a minor weakness in the organization. Compared to other companies in the Automobiles industry and the overall market on the basis of return on equity, HONDA MOTOR CO LTD has outperformed in comparison with the industry average, but has underperformed when compared to that of the S&P 500.

F ChartF data by YCharts
3. Ford Motor Company (F)

Rating: Buy, B
Market Cap: $60.8 billion
Year-to-date return: 1.3%

Ford Motor Company manufactures and distributes automobiles worldwide. The company operates through two sectors, Automotive and Financial Services. The Automotive sector develops, manufactures, distributes, and services vehicles, parts, and accessories.

"We rate FORD MOTOR CO (F) a BUY. This is driven by some important positives, which we believe should have a greater impact than any weaknesses, and should give investors a better performance opportunity than most stocks we cover. Among the primary strengths of the company is its generally strong cash flow from operations. We feel its strengths outweigh the fact that the company has had lackluster performance in the stock itself."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • Net operating cash flow has slightly increased to $2,413.00 million or 8.69% when compared to the same quarter last year. Despite an increase in cash flow, FORD MOTOR CO's cash flow growth rate is still lower than the industry average growth rate of 23.55%.
  • Regardless of the drop in revenue, the company managed to outperform against the industry average of 6.9%. Since the same quarter one year prior, revenues slightly dropped by 5.5%. The declining revenue appears to have seeped down to the company's bottom line, decreasing earnings per share.
  • FORD MOTOR CO' earnings per share from the most recent quarter came in slightly below the year earlier quarter. The company has suffered a declining pattern of earnings per share over the past two years. However, we anticipate this trend to reverse over the coming year. During the past fiscal year, FORD MOTOR CO reported lower earnings of $0.78 versus $1.75 in the prior year. This year, the market expects an improvement in earnings ($1.59 versus $0.78).
  • The gross profit margin for FORD MOTOR CO is rather low; currently it is at 18.58%. Regardless of F's low profit margin, it has managed to increase from the same period last year. Despite the mixed results of the gross profit margin, the net profit margin of 2.72% trails the industry average.
  • Return on equity has greatly decreased when compared to its ROE from the same quarter one year prior. This is a signal of major weakness within the corporation. Compared to other companies in the Automobiles industry and the overall market on the basis of return on equity, FORD MOTOR CO has outperformed in comparison with the industry average, but has underperformed when compared to that of the S&P 500.

TM ChartTM data by YCharts
2. Toyota Motor Corporation (TM)

Rating: Buy, A-
Market Cap: $215.7 billion
Year-to-date return: 9.2%

Toyota Motor Corporation designs, manufactures, assembles, and sells passenger cars, minivans, commercial vehicles, and related parts and accessories in Japan, North America, Europe, Asia, and internationally. It operates through Automotive, Financial Services, and All Other segments.

"We rate TOYOTA MOTOR CORP (TM) a BUY. This is based on the convergence of positive investment measures, which should help this stock outperform the majority of stocks that we rate. The company's strengths can be seen in multiple areas, such as its solid stock price performance, growth in earnings per share, increase in net income, attractive valuation levels and good cash flow from operations. We feel its strengths outweigh the fact that the company shows low profit margins."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • The stock has not only risen over the past year, it has done so at a faster pace than the S&P 500, reflecting the earnings growth and other positive factors similar to those we have cited here. Turning our attention to the future direction of the stock, it goes without saying that even the best stocks can fall in an overall down market. However, in any other environment, this stock still has good upside potential despite the fact that it has already risen in the past year.
  • TOYOTA MOTOR CORP has improved earnings per share by 16.8% in the most recent quarter compared to the same quarter a year ago. The company has demonstrated a pattern of positive earnings per share growth over the past two years. We feel that this trend should continue. During the past fiscal year, TOYOTA MOTOR CORP increased its bottom line by earning $11.46 versus $11.17 in the prior year. This year, the market expects an improvement in earnings ($11.99 versus $11.46).
  • The net income growth from the same quarter one year ago has greatly exceeded that of the S&P 500, but is less than that of the Automobiles industry average. The net income increased by 15.7% when compared to the same quarter one year prior, going from $3,204.00 million to $3,708.00 million.
  • The return on equity has improved slightly when compared to the same quarter one year prior. This can be construed as a modest strength in the organization. Compared to other companies in the Automobiles industry and the overall market on the basis of return on equity, TOYOTA MOTOR CORP has outperformed in comparison with the industry average, but has underperformed when compared to that of the S&P 500.

THO ChartTHO data by YCharts
1. Thor Industries, Inc. (THO)

Rating: Buy, A
Market Cap: $3 billion
Year-to-date return: 4.3%

Thor Industries, Inc., through its subsidiaries, designs, manufactures, and sells a range of recreational vehicles, and related parts and accessories in the United States and Canada. It operates through two segments, Towable Recreational Vehicles and Motorized Recreational Vehicles.

"We rate THOR INDUSTRIES INC (THO) a BUY. This is based on the convergence of positive investment measures, which should help this stock outperform the majority of stocks that we rate. The company's strengths can be seen in multiple areas, such as its revenue growth, largely solid financial position with reasonable debt levels by most measures, notable return on equity, good cash flow from operations and impressive record of earnings per share growth. We feel its strengths outweigh the fact that the company has had lackluster performance in the stock itself."

Highlights from the analysis by TheStreet Ratings Team goes as follows:

  • The revenue growth came in higher than the industry average of 6.9%. Since the same quarter one year prior, revenues rose by 12.2%. Growth in the company's revenue appears to have helped boost the earnings per share.
  • THO has no debt to speak of therefore resulting in a debt-to-equity ratio of zero, which we consider to be a relatively favorable sign. Along with the favorable debt-to-equity ratio, the company maintains an adequate quick ratio of 1.48, which illustrates the ability to avoid short-term cash problems.
  • The return on equity has improved slightly when compared to the same quarter one year prior. This can be construed as a modest strength in the organization. In comparison to the other companies in the Automobiles industry and the overall market, THOR INDUSTRIES INC's return on equity significantly exceeds that of the industry average and is above that of the S&P 500.
  • THOR INDUSTRIES INC has improved earnings per share by 15.5% in the most recent quarter compared to the same quarter a year ago. The company has demonstrated a pattern of positive earnings per share growth over the past two years. We feel that this trend should continue. During the past fiscal year, THOR INDUSTRIES INC increased its bottom line by earning $3.28 versus $2.86 in the prior year. This year, the market expects an improvement in earnings ($3.79 versus $3.28).
  • The net income growth from the same quarter one year ago has greatly exceeded that of the S&P 500, but is less than that of the Automobiles industry average. The net income increased by 14.0% when compared to the same quarter one year prior, going from $55.12 million to $62.85 million.

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